Re: Alternative Lesson: "Never turn anything off if..."
However, if a power failure needs serious effort or hardware fixes to get it going, its a shit system.
Who here has not see a UPS fail and simply take out the supply instead of going to bypass? (Think of any unfortunate APC owners)
Or, less commonly, a local digger has JCB'd the local 11kV feed and your power is off for hours and UPS exhausted? (Generators are available, some of them might even work when needed)