Originally Posted by dartgande
Interesting. Just removed CMOS battery and put it back in slot. Computer won't power on at all now. Bad battery, perhaps?
A bad battery will not cause what you're seeing. A bad battery would cause it to give you an error that the battery has an issue. If there is no power to anything now, I would suspect the power supply, then the motherboard, in that order. Power supplies can do some weird stuff if the voltage isn't right. It can also fry a mobo. Swap a test power supply into that thing and see if it fires up. Make sure all of the connections are in (particularly the two power cables for the mobo as you'll get absolutely nothing without those).