Dead computer?

[Archangel112]

I thought my computer was well, dead after running it with a PSU that was too weak, it wouldn't come on anymore, no noise apart from when i switched it off, i baught a new PSU, nothing untill now. I decided to see if the LED's were connected properly, they weren't I hooked them upright with a new PSU and now everything appears to startup. CPU fan and PSU. I plugged a monitor into it and nothing. The LED on the front is solid red.
I'm not too sure what the specs are anymore, I guess that doesn't help.

Thanks in advance