Re: Am I missing something
Hell, I run a double conversion UPS with backup generator (tested once a month) and these are for our personal devices! I can understand how what happened to them happened, from personal experience in the US Navy*, but people fails do happen in addition to hardware fails and in these types of situations you double-check everything each step of the backup/restoration process.
* reverse power breaker didn't trip during generator reverse-power detection test. Every piece of online electronics became a nice, very short lived battery to that generator turned motor. Ever seen solid insulation turned into a messy PCB soup, gaping holes in circuit boards and, even better, plugs literally blown off the equipment. Fun!