This very much reminds me of what was said by TV repairmen in the days of the "house call." They said that it would amaze you how many times they went to a house only to find out that the TV had been unplugged and that was the only problem. Usually the housewife unplugged it to plug in the vacuum cleaner and forgot to plug it back in.
As a radar repairman in the Army, we called such "cockpit errors."
Have a great day,