The power went off a couple of times this week, once in a storm, but the other day just randomly, except a breaker in the box outside didn't flip. The UPS was acting up, and last night I decided to check it out. It's a CyberPower unit that is addressable via a USB cable to the computer.

I opened the software and it said it was running normally so moved to the next tab and told it to run the self-test feature, and two seconds later there was a small explosion and the battery inside the device burst into flames. It was out in moments as I yanked off all things attached to it and lugged it into the yard. The replacement is the same thing, newer model (I read a lot of reviews before going with this again). Sine wave, AVR, and the battery is replacable. The ones in the old device were replaced (name brand) several years ago (my Amazon purchase history shows a replacement from five years ago - that seems a very long time for a battery to be in service.) I think the age of the battery was the problem - and something I'll need to make a note about checking more often. There is computer security and then there is computer security!

The new UPS arrived this morning and is charging now.