Help: 15" Tibook not powering on--PRAM battery?

I have a Tibook 400 that I broke the power socket on, so the laptop wasn't getting power (battery wasn't charging, etc). So, I bought a new logic board on Ebay (it's a 500MHz board, so I got a speed boost out of the deal as well). The logic board swap was pretty tricky, but seems to have worked ok--the main batteries are charging now, but the machine is otherwise dead--no response at all when I try to power it on.

It sat for several months with no power whatsoever (no AC, no battery). Is it possible the PRAM backup battery has died? Is that something that would produce the symptoms I'm seeing?

Thanks!