I would be suspicious of a thermistor. Sometimes these main boards get a glitch in them and disrupting power will reset. I would wonder if customer is unplugging unit in an attempt to solve problem and maybe not mentioning to me. It's obvious that it is a temporary no cool issue where it's melting and re freezing. Most often when these no run glitches occur, they will not turn back on without a disruption of power. Had one that was completely dead in the water for four days. I unplugged for a couple minutes and like brand new now for over a year or else I would have heard. Sometimes a faulty board can be difficult to detect. I'm always looking for test boards to put in my truck. I have alot. If this job was easy, everyone would be doing it. Good luck. Let's us know.