Whilst it could be a BIOS problem I would have thought this unlikely?

Can you get hold of a floppy boot disk and see if it will boot into DOS. I would try this with the hard drive connected and disconnected if that doesn't work.

You mentioned that you had reformatted the hard drive? so that might be where the problem is? I would try putting the hard drive into another machine, and see if it boots.

It might also be worthwhile trying a different video cable.

When you try to bood do you get lights and noise from the hard drive..........if so, how long for?

Cheers