Originally Posted by MisterKeeks
At my school they dug up an old G3 AIO
which "does not power on" (I'll test it in more depth tomorrow). My theory is the presumably dead PRAM battery may be preventing it from starting up, like in the G3 PowerBooks. Is this possible?
No, not necessarily. It can be the SMC, the Power Supply, or even the Logic Board. First try resetting the SMC (unplug the power cord, hold the power button for 5 seconds, re-insert the power cord) and if it doesn't work, try changing the PRAM battery.