MacBook stuck on grey screen, help?!

Hello, I have MacBook which is stuck on the grey screen - we can hear the fans and sometimes the hard drive spinning, but that's it. We can shut it off, but when you turn it on you just get the grey screen - no spinning wheel, no apple, no question mark, nothing.

The hard drive is not toast, we took it to someone who took it out and were able to put it in another machine and recover data from it with no problems.

Additionally, the keyboard on it broke some time ago and we've been using an external keyboard attached to the USB port, could this be why single-user-mode and safe-boot-mode aren't working?

Things we have tried which made no change:
* took out battery, held down power key for 5 seconds, put battery back in
* held down shift key when starting up
* held down Command S when starting up
* held down Command V when starting up
* held down Option Commend when starting up
* held down Shift S when starting up
* zapped the PRam

Is there anything else we can do? None of these did anything, we still just got the grey screen, same as before. I've never had a computer which wouldn't start in single-user-mode! Could it be because the keyboard is external?

Any suggestions would be very much appreciated!

Thanks,

Alyssa

Two possible defects could cause what you're experiencing:

A defective hard drive. Note that it's possible to remove a drive that won't boot from a machine and get data off it. That does not prove your hard drive is OK.

The second thing that comes to mind is you could have a dead logic board. If that's true you're looking at a very expensive repair if your machine is not covered under warranty.

Regards.