3 ms·

OP mentioned PC was off. Feels way overkill.

• Nextgrid 5y ago
  Was it off or merely on standby, susceptible to be woken up by USB activity (even slightly touching the mouse would be enough) or scheduled tasks (Windows update, etc)? I'm suspecting it was on standby, woke up at some point but the monitor turned off due to inactivity even though the machine was on at the time (or turned itself off again later after the incident happened).