Here’s a peek at what damage those little power cells can wreak on poor unsuspecting motherboards. It just happened to be an LC 475 as well, didn’t it? Not mine thankfully! :P

Apple specified a 3.6V lithium PRAM battery for the LC 475. Old lithium batteries in stored vintage Macs are worth inspecting and removing where appropriate, as leakage can cause serious logic-board damage. Handle and dispose of lithium cells carefully rather than treating them like ordinary rubbish.

Sources