@ Thor.

Check post 2280 in this thread.

Hopefully it might help.

Looks like youve tried everything else but just in case:

Disconnect PSU cables

Remove battery for 15 min

Then reassemble with only one stick of ram in the second closest slot to CPU and minimum other components (VGA + PSU + CPU + Cooler) and try to boot.

If successful switch to bios 2 (cant remember how, check manual).

If not successful try another stick of ram in same slot.

Good luck