Always keep your disaster plan up to date
"Thinking through all this, I took two very slow gentle steps toward soasto not make waves, and carefully held down the UPS's power button for what felt like several minutes, but was probably only 5 seconds.
PCs went off, and all was well. I should have just switched off the building mains - know for next time."
We had a flood thanks to developers on the industrial estate cutting through a water main when demolishing an old building. The Disaster plan procedures were followed and the mains power was shut and padlocked off.
Unfortunately the disaster plan procedures were written before the server room got a containerised back up generator that automatically powers up and keeps the servers alive when the mains power goes off.
Thankfully the resulting voltage tango was non fatal.
Lessons learned. Robust procedures etc etc etc.