I worked tech support that included a device for software developers that had Ethernet connectivity. I learned very quickly to say "Try reseating the Ethernet cable" because if I said "Is the Ethernet plugged in" about 1/3 of the people would respond very negatively (e.g. "I'm not a fucking moron") but by having to reseat the cable, they would sometimes discover it's not plugged in.
The classic way to get the consumer to power cycle the hardware is to ask them which color ring is at the base of the DC plug. It doesn't really matter what color it is, what matters is that it was removed and the hardware definitely restarted.
I once has this happen with my father's new standing desk. He, PhD with an Electrical Engineering degree, couldn't get it working. Turned out the C13 power cable was only 90% inserted, and felt firmly in place but did not have enough connector to power the desk.
I’m sure we’ve all been caught trying to troubleshoot a problem where the actual issue was a loose cable.