A standard question with phone- or online-based troubleshooting is to ask the user if the misbehaving gear in question is actually plugged in. Sometimes they take the implication less than kindly. But here <https://forums.theregister.com/forum/all/2020/09/04/on_call/#c_4102668> is a wonderfully tactful way to phrase the question: If it was obvious from the phone call that the power wasn't on, she would tell the user that they'd had problems with a batch [of] power cables and ask them to check the serial number on the wall plug. After a minute she usually got a sheepish reply that the problem seemed to have gone away....