If that mouse crossed the + and - it would have met 540DC in a moment. Yes Thomas Edison, it will kill you.
I’ll bet the batteries survived.
They did.
But the charred mess of mouse, smoke, tripped breakers, some fuse somewhere that I was told about but didn’t see, and the charred remnants of nesting material on top of the battery were “interesting”.
It looked worse than it actually was.
But ugh, the smell.