You said that the power supply fans weren't running. (Hint, hint). If the power supply gets too hot or figures out that something is wrong, it will shut down.
Hoping it is just the fans, can you give them a spin (not with your finger) to see if they want to go, or are they dead? Maybe it is just a case a dustballs mounting your fans!
If a CD drive shorted out, that would send an error signal back to the poer supply too. Can you start it up with just your floppy drive? Can you get into the bios?
Glenn