I bought a Mac

Just a trick out there for the pram-frusturated, on my very own G4 pinstripe I was able to get it working without a (correct) battery, instead alligator-clipping on a pack of 3 triple a batteries. Worked like a charm (Connecting three AAA batteries in series [1.5V + 1.5V + 1.5V] provides a total of 4.5V, slightly exceeding the required 3.6V but it did work, and for a while). RIP if you want to revive a TIbook battery though.

You can just hold down <apple>+<option>+<P>+<R> at boot and let it play the boot sound a few times before releasing. This will reset the PRAM battery, and allow it to boot to desktop with a working monitor if the PRAM battery is flat.