A thing of horror: an UPS rack vs one enterprising mouse.
Only saw the results, and that was in passing.
The rack tech was cussing a blue streak.
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.
It doesn’t sound like the battery cabinet. We convert the DC to AC. That mouse probably got in touch with an AC output.