You can try a logic board reset, by removing all the power to the board for as long as possible. Remove the spare battery and don't plug it into the A/C converter. Remove the battery on the board (I honestly cannot remember if it has one), and this will reset the board if you wait 10-15 minutes without power. One to five minutes is acceptable, though a little longer does not hurt.

When the machine starts back up, make sure you have a bootable CD in the drive, and hold down the 'C' key. You will want to plug that keyboard in for that part. If that does not work, then you maybe dealing with another issue alltogether. I'm glad you get some video now and what seems to be salvagable machine.
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MacBook 2GHz Intel Core 2 Duo w/ 2GB DDR2 RAM & 120GB SATA 5400RPM HDD
Canon Rebel XTI
Google Cr-48 Beta Laptop