Had a rummage on the net and came across the manual here: -ftp://ftp.aopen.ru/pub/manual/mb/mx4ge/mx4ge-ol-e.pdf
All i could think of atm is: -
1. Resetting the CMOS
2. Some m/b's will refuse to boot up unless a fan is attached to the headers.
3. There's something about a resettable fuse on the top-right corner?
Otherwise, i think you've tried everything else and just, well SOL.