As Mac.Genius said, best option is to try and boot into Target Disk mode (connected to another mac) to backup files/clean the HD. When you boot into TD mode, it'll be like mounting any other HD, so you can wipe it/format it, re-install OS, etc. I just dropped my MBP off to be repaired for the same problem (no video/black screen) and this worked for me!
Edit: You can pop the install disk into the other mac (probably best option). OR, as I had to do in my case (old Mac mini didn't like the DL-DVD), you can actually put the disk into the mac you have in Target Disk mode and boot off of that through the other computer (it'll mount, and then you just choose "install Leopard" or whatever OS version you have- and it'll automatically ask you to boot (will take awhile to do so, btw).
*As far as I know, this would probably have to be with the official Mac OS install disk, not with the disk(s) that came with the MBP.