I have a pretty old computer (aprox. 5 years). 1.6gig P4.
HERE'S WHAT I DID:
I took the 56k modem pci out. After I took it out, it worked fine. When I put it back in and pressed the power button, it won't even turn on (no flicker, nothing). Also, when I took the modem out, the little screw that screwed the card to the slot was dropped and got stuck underneath at the edge of the motherboard. I poked at the motherboard a few times to get the screw out and finally got it out. The poking was soft and there was no physical damage to the motherboard as far as I can see. I reseated all cables inside and seems like the power supply is working fine because, I can see an LED light come on and off on the mobo if I plug and unplug the power cable and the ethernet port LED light is lit up.
By poking at the edge of the mobo just to pry the screw out can damage the whole power supply? Could it be the internal lithium battery? I ran out of options. Any suggestions would help. Thanks in advance.