My friend has an old computer which doesn't boot. When you press the power switch, the fans start, and the power light goes on, but nothing happens. The monitor works, but it stays black, and there is no sign of any BIOS or any other activity. I think it is that the BIOS is broken. (is that possible?)
If it a simple loose wire, or chip, which one could it be? Or is something physically broken?
NOTHING will boot. The fans run, but nothing else.
(I know this is not linux-specific, but I am trying to run Linux on it, and I just thought that someone reading this might be able to help.)

It could be any number of a million things... loose power connector on a hard drive, bad CPU/Memory, poorly seated CPU/Memory, bad PCI card or video card, poorly seated PCI card or video card.... ect. ect.

One thing to try... take the whole thing apart and put it back together again and see if that helps...

If possibly try a minimal configuration (one stick of memory, video card, no hard drive..) See if it'll post that way.