Powermac 6500 dead PRAM battery?

So I dusted off my old 6500 from storage recently and booted it up to experience some good old fashioned nostalgia. The system seemed to be acting a little funny, so I tried to restart it. But it never turned on after shutting itself off. I've tried pressing the CUDA button, but I can't even get the fans to start spinning. There's dead silence. From looking through these forums, it seems that it might be a dead PRAM battery, but the Rayovac one that is used in this computer is no longer being made, and I'm not even totally sure it really is the PRAM. Maybe the power supply is fried from being left unpowered so long? There are some third party venders for 4.5V batteries, but I'm skeptical. Has anyone bought a replacement third party PRAM battery and have it work well? I'd really like to hear some experiences on this.

I'm also thinking of potentially making my own 4.5V from 3 AA. From what I remember in physics I'm suppose to connect 3 1.5V's in series and the volts will be additive. Then I'll just connect the ends to the connector from the dead battery. Does anyone know if this will work? Will the difference in battery amps make this not viable?