But it's worth repeating in this context. Thankfully, it wasn't me.
When I worked at a KC bank, we had a Wire Transfer team manager who loved golf. He was supposed to come in Saturday and test a firmware/OS upgrade, then restore. Nice, sunny day Saturday, so he decided golfing would be better.
Came in Sunday. Installed firmware/OS upgrade. Tested fine. Forgot to reinstall previous firmware and powered up old OS.
Incompatible. Froze the machine solid. He panicked and tried for maybe four hours to fix things himself. No go. Finally called Cupertino for help 4+ PM.
The techs had to be found, gathered and flown out from CA to disassemble said machine and reassemble. No wires until 1 or 2 PM Monday. Much money loss for all customers.
To answer the obvious question, no - beyond my understanding, he wasn't fired or even demoted.