have you checked to make sure your CMOS jumper is still there? - this has stumped me with the same problem you're reporting
also, though im guessing you have checked this; are the power buttons wired up correctly?
Hope this helps
CMOS jumper still there, I tried resetting it a few times without any success...
Power button I think is wired up correctly, black is negative and colored is positive...
What happens with your on-board reset switch, does it stay on or powers off?