Some connection seems to be flaked. And it's heat dependent. You turn it on, and it heats and faults out. Sounds like a break in a soldered pad. It'll look okay but it's separated and with any heat lifts. Those are difficult to find. That is my best guess (had a projection screen TV that did this. Took us months to find where it was. One sizzle with a soldering iron fixed it) Did you contact the manufacturer?