i bought a macbook (i think 2006) for like 40 dallors and wanted to try to fix it. The problems that are coming up thought are weird and not consistent. Somtime i can log in and do stuff for a couple minites and then it will kick me off. Sometime it will load up but the screen won't be back light. Sometimes the error will show that there is no bootable drive. I've tried booting from a disc but it never worked. It just sound like it eating the disc. I've holding down d to boot into the test system menu but never worked. Also running this without a batterie since the one i got was shot. I know this is proble a hard question to answer but thank for looking at it.
Find the original OS X DVD that came with the system that says in small print on the label 'AHT Version x.x'. Insert that one and reboot holding the alt/option key down. Choose the Apple hardware test, and when prompted, choose the extended test. It can take over an hour to run.