Time for that reminder again. You may have pulled the leaky 1/2AA batteries from your Macs, but have you re-applied thermal compound? It can dry out to barely more than dust, and the last thing you need after pulling a classic machine out & firing it up for the first time in years is thermal damage because it just couldn't cool itself.
@NanoRaptor aw yes the quad CPU Power PC G4. What a classic.