Eleven years

The mistake

Russ powers down a device without first checking what depends on it, because nothing about the box indicates its function and there's no asset record or wiring label to consult. It turns out to be the controller for the building's badge-access door lock, so killing power to it also kills the door, with no documented fallback or manual override. On restart the controller comes back up requiring an admin password that was set once in 2019 and never stored anywhere retrievable, so there's no way to reauthenticate it.