Mobo

PC specs:
333 PII
128 RAM
6 Gb HD

Win 2000 w/sp3

Just upgraded to win 2000 sp3
everything worked Ok the first 3 reboots and then I rebooted the 4th time and there was no power light and the hard drive light remained constantly on.

When I booted up there was no POST
I have tested the power supply-OK
I have disconnected all expansion cards and booted with Mobo, RAM, and Video-no post
I have used another Mobo to test the power supply-OK

Question. Does it sound like my Mobo is fried based on the info given or should I try something else?