Please Help: Laptop Computer Shuts Down After Powering Up

Good Voltage

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Hello.

I am using a Dell N4050 (a laptop). The computer is having lots of troubles powering up, and it also shuts down suddenly. I elaborate on the problem below. I ask for your help, please see the questions at the end.

Background: I use the computer almost always connected to the power supply, instead of on its battery. I have been using this computer for more than 1 year; it gets around 8 hours of usage per day. The built-in keyboard no longer works since around 3 months ago when I cleansed it throughly with a wet tissue and apparently some water leaked and broke it (I was careful that no water made it past the keycaps, but the fact that it stopped working makes me think it happened). Now I use an USB keyboard. The built-in keyboard occasionally signals spurious keystrokes, so I had to block it in software. The computer has never fallen, had water dipped on it (except possibly for the ill fated keyboard cleansing) or been run on battery until charge run outs.

Symptoms: 3 days ago, my computer powers off suddenly while I went to do something else. I turned it on again with no immediate problems, and it worked fine for around 30 minutes, but then again it powered off suddenly. I tried to power it on again, but this this time, after turning on, showing the "power on" LED, and making the usual boot noises for like 1 second (not enough for the BIOS splash screen to show) it powered off. I insisted trying to power the computer more than 10 times in a row, and the same thing happened every time except for a few occasions where pressing the "power on" button had no effect what so ever. I left it rest for 1 hour, with the power cable disconnected then turned it on and it worked fine for that day.

Today my computer has again suddenly powered off while I was using it, in the same way as if I unplugged a desktop (but this is a laptop). I tried to power it on pressing the button more than 50 times with no success; pressing the button now had mostly no effect except for around 1/10 attempts resulting in the already described "power-up for 1 second"; then I tried all combinations of letting the computer rest (for at least 30 min each time) with and without the power cable, and trying to power it on with and without the power cable. After several hours of trying (most of it is rest), it finally powered on all the way to the OS, but powered off suddenly after ~5 min. I continued the aforesaid rest/try-to-power-on procedure. Finally, it powered on without the power cable and with the external USB keyboard disconnected, but I connected the keyboard (since it is otherwise useless) and it is currently working allowing me to write this message (>1 h uptime so far).

The computer wasn't particularly stressed during, before or after either incident (I was using it for browsing with minimal CPU usage, and there wasn't any power outage, brown-out or similar, the ventilation path is unobstructed). I noticed that every time it shuts down suddenly, there is a "tick" heard, like when you connect or disconnect loudspeakers to an amplifier. Maybe it is actually made by the built-in loudspeakers ad the built-in amplifier is suddenly unpowered. There isn't the characteristic smell of exploded capacitors.

In summary: The problem is that the computer suddenly powers offs, but after much trying and letting it rest, I could make it work, but I am still asking for help because I think it will soon stop working at all.

Questions:

  • What component is more likely to be causing the problem?.
  • Is it possible that the built-in keyboard is causing a short circuit that forces the PSU to power off?. How high do you judge the possibility?. Please note that the keyboard has been broken for 3 months but the power-off problem just started.
  • In case the motherboard is the problem, is it feasible to replace it or do I necessarily have to get a new laptop if the motherboard stops working?
  • What can I do to try to fix or work around this problem without having to purchase new components (like resetting the BIOS and similar)?. I will have to try all that can be done to the computer, because it is extremely hard for me to get a new computer (I can't simply buy one in a local shop because I am in an exceptionally limiting situation); this is currently my only computer.
Notes:

  • Please do not hesitate in using technical language. I am familiar with computer hardware, as I have assembled and serviced my former desktop computers (but they are broken and I can't repair them for the same reason I can't simply purchase a new computer).
  • I have backups and I am aware that the hard disk and my data is likely not gone with the computer, but I do not have another computer to plug the HD or use the backups.
  • I use GNU/Linux (commonly miscalled "Linux", that is actually the name of the kernel only).
  • I have discarded the OS as the problem, because the problem is manifested before the BIOS splash screen shows, well before the OS or bootloader is running.
Thanks in advance.
 
Since you've said that you spilled water in the keyboard and have had issues with it ever since, I'm inclined to think it's very possible this is the source of the issues. If liquid made it's way to the motherboard, possibly it is causing a short somewhere that is leading to these issues.

It also sounds like a possible overheating issue? have you verified that the fan is still working correctly? Download coretemp and verify your temps are in an acceptable range.

You said that you always leave it plugged in. If it has a good battery, do you have any different results running off the battery instead of AC? You could use a multimeter to verify consistent voltages from your AC adapter, or try a spare if possible.

If it's neither the charger or the temperatures I'm betting your motherboard is failing. Even though the keyboard is damaged, I would doubt that leaving it plugged in is shorting the board, but if you feel comfortable flipping it over and unplugging it you can find out for sure.
 
Thanks for replying.

Since you've said that you spilled water in the keyboard and have had issues with it ever since, I'm inclined to think it's very possible this is the source of the issues. If liquid made it's way to the motherboard, possibly it is causing a short somewhere that is leading to these issues.

I see, but given that the keyboard incident was 3 months ago and the power off problem just started, do you still consider this the most likely source of the problem?. It was not a lot of water like an spill. If the keyboard problem was due to water, it would have been that some of the wetness of the tissue made it past the keycaps. Are laptop keyboards closed on the bottom?.

You said that you always leave it plugged in. If it has a good battery, do you have any different results running off the battery instead of AC? You could use a multimeter to verify consistent voltages from your AC adapter, or try a spare if possible.

I checked the charger voltage and it is within 0.2 V of nominal, so I think that it is working fine. There seems to be no difference between running off the battery and charger, but maybe coincidentally, when the computer finally powered up after much insistence when it gave problems, it was with the charger disconnected.

It also sounds like a possible overheating issue? have you verified that the fan is still working correctly? Download coretemp and verify your temps are in an acceptable range.

I use lm-sensors. I forgot to mention that it does not seems to be a thermal problem. All temperatures are 57.0 °C or cooler, which is well below the reported "high". The fan is working; I feel the air current around the laptop's vents.

How likely do you think that the problem is that the PSU is failing, instead of the motherboard?. In your experience, how much often do you see either component fail instead of the other?.

I appreciate the reply; nonetheless I am also interested in what other forum members would say about this problem, given that different experiences often give us more insight into troubleshooting. Thanks in advance.
 
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Hi! I agree with crazyman! I'm also wondering if you have tested any of your hardware. You could try sea tools if your PC will stay on long enough. If it passes sea tools, then you can rule out the HDD! Here's link for sea tools!
SeaTools for Windows | Seagate

SeaTools for Windows

SeaTools for Windows is completely data safe. It installs on your system. If the drive passes SeaTools for Windows, your troubleshooting can move to other areas.
 
Hi! I agree with crazyman! I'm also wondering if you have tested any of your hardware. You could try sea tools if your PC will stay on long enough. If it passes sea tools, then you can rule out the HDD! Here's link for sea tools!
SeaTools for Windows | Seagate

Thank for replying.

I see that SeaTools it is for Windows while I use GNU/Linux. More worryingly, it is proprietary software (you can search the term using a search engine and find a lot of information, also called "non-free software") which I avoid because it is under the control of the developer (like Windows, OS X and most software for those OSs) and not under the control of the user as GNU/Linux is (anyone can use GNU/Linux unhindered by the developer, see the source code, make modifications, or reuse the code for other purposes that is how it is developed). You can see how much control they want to have over my computing if I use their software by reading their EULA. I have refused to hand the control of my computer to any individual, megacorporation or otherwise, and that is why I use GNU/Linux.

Instead I performed a full test disk with smartctl from smartmontools which is a free (as in freedom, and also free of charge) tool for GNU/Linux to perform hard disk monitoring and administration including scanning for problems; it reported no problems with the hard disk. This particular hard disk has never given me any problems.

Apart from that, I have tested the charger as crazyman143 suggested. Since I do not have other computer, I can not test the components one by one in a different computer.

Regards.

Has anyone experienced a problem like mine when the computer powers down after around 1 second of being powered on?.
 
Hi You can also do a Memory diagnostic test. Testing with Memtest86+ would be better, but you might give this a try for now!!
How do I know if my computer has a memory problem?
You might give this a look and see if any thing here could help!!
Product Support | Dell US

Remember I use GNU/Linux. I would not hand control over my computing and by extension of my life (to a big extent) to Microsoft or any other megacorporation or individual. I will use Memtest86+, thanks for the recommendation.

I have checked the laptop's manual already. Apart from instructions on how to remove the parts (which is useful), there isn't anything helpful in troubleshooting.

Thanks for replying.

P.S: I posted another reply but the forum software replied that it was put in queue to be approved by a moderator; that was unexpected. It did not include insults or anything similar.
 
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Hi! I agree with crazyman! I'm also wondering if you have tested any of your hardware. You could try sea tools if your PC will stay on long enough. If it passes sea tools, then you can rule out the HDD! Here's link for sea tools!
SeaTools for Windows | Seagate

Thank for replying.

I see that SeaTools it is for Windows while I use GNU/Linux. More worryingly, it is proprietary software (you can search the term using a search engine and find a lot of information, also called "non-free software") which I avoid because it is under the control of the developer (like Windows, OS X and most software for those OSs) and not under the control of the user as GNU/Linux is (anyone can use GNU/Linux unhindered by the developer, see the source code, make modifications, or reuse the code for other purposes that is how it is developed). You can see how much control they want to have over my computing if I use their software by reading their EULA. I have refused to hand the control of my computer to any individual, megacorporation or otherwise, and that is why I use GNU/Linux.

Instead I performed a full test disk with smartctl from smartmontools which is a free (as in freedom, and also free of charge) tool for GNU/Linux to perform hard disk monitoring and administration including scanning for problems; it reported no problems with the hard disk. This particular hard disk has never given me any problems.

Apart from that, I have tested the charger as crazyman143 suggested. Since I do not have other computer, I can not test the components one by one in a different computer.

Regards.

Has anyone experienced a problem like mine when the computer powers down after around 1 second of being powered on?.
 
Sorry! I missed the part about Linux. I don't have any more suggestions for you.
I'm sure the forum has members that use the Linux OS. As far as shutting down, I would think there are many things that could cause that. I'm starting to wonder if you came here looking for help or maybe to show us what all you know.
Any way I hope you get your problem solved!
Gary!
 
Sorry! I missed the part about Linux. I don't have any more suggestions for you.
I'm sure the forum has members that use the Linux OS. As far as shutting down, I would think there are many things that could cause that. I'm starting to wonder if you came here looking for help or maybe to show us what all you know.
Any way I hope you get your problem solved!
Gary!

No, I am asking for help, of course. Apologies if it looks like I said something pretentious that makes you think otherwise. I mentioned the reasons of why I avoid Windows because I think they are important, but I took your advice and used the equivalent program on GNU/Linux, then I elaborated so as to explain why it is the equivalent (not to show that I am knowledgeable or similar)

Thanks!.
 
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