96 c220 won't start
 

The car cranks but won't fire. I tried everything in the manual about start lock and locking/unlocking with/without the remote/regular key in both the door and the trunk...nothing helps. So I had it towed to the dealership and after checking EVERY wiring point in the car (so they say) they want to replace the HFM control unit for $1400, just for the part. Everything I have read on this site tells me it's the OVP. Any suggestions?

I'd love nothing more than to fix it myself if I just new what the problem was. Thanks