My sister needs a computer. I've got an old PowerBook that was great when it worked. I repaired it to give to her.
It took a while. Initial checking of advice on the web suggested that the PRAM battery might be the problem. It wasn't. The main problem turned out to be a corrupted hard drive that that had gone south. I had to boot from another Mac in target mode to use Disk Utilities because the PowerBook optical drive is mechanically dead too. Your repair guide helped me disassemble the optical drive and recover my System Restore Disk and replace the hard drive in addition to replacing the PRAM battery.
I should have tried booting from the System Restore disk in another Mac running in firewire target mode right off the bat. I could have run Disk Utilities. I would have discovered the HD was dead right away and saved the cost of the PRAM battery. Still - it only cost $85 in parts and materials to get the PowerBook going again. Also, I should have spent an extra $60 to put in a SSD. It might have been almost as fast as today's computers! Oh well.
I want to thank ifixit and the Apple Support Community. Another good source of info.
As an aside, the ifixit Spudger is one of the best cheap (read inexpensive) tools to add to you toolkit. It works great for disconnecting PC board ribbon cable connectors or when a non-conductive probe is needed! I should have got two or three of them.