Ah, there was an empty slot where a battery should go; really big ones.

[ He makes a motion with his arms to illustrate, it was not quite the size of a car battery. ]

Probably about this big all together, should have held five of them.

And a crank above it - we turned it, thinking it might've had some backup power source. I think it might be a generator. Wouldn't that be nice, we could find lights!