Monitor Stays dark, when startup

Windows 2K, 3HDD, biostar P4M900-M7,2gb Mem
Removed cables, re-seated memory,changed jumpers, changed battery,when it finally does boot up, the monitor lights up, boots ok to desktop. When I shut down, I can restart again and again. The next day the problem still exists. I have had to take a key and run it across the neg/pos posts of the power plug to demagnetize it. Then it worked.. Today, I tried that and it stopped working. Can't figure out the problem, maybe you have a solution

Any suggestions welcome

thank you

 

Try going into the BIOS and find the "Defaults" setting.

Have you disconnected all extra drives? Removed any PCI cards, etc?

Don't discount that the power supply may be failing.

Hopefully, the "hardware" won't be the motherboard. Seems that something works when it is warm, not when it's cold.

Matt