Dead Samsung UN55TU8000F

If I were to hazard a guess, that TV got spiked at some point. It may be as simple as a frozen relay in the starting circuit, a fusible link or similar. Repeat: S.W.A.G. Guess.

Peter Wieck Melrose Park, PA

I've stopped taking in all TU series Samsungs because most have bad display screens. Symptoms are from random shutdown and restart (with tell-tale very fine horiz lines in the pic as viewed up close) to no picture, just constant rebooting on plug in.

If the TV cycles the back lights every 15-20 seconds or so by itself, it's probably a bad display. Unplug the ribbon to the display and see if the back lights stay on.

I unplugged the ribbons, same thing - backlight flash at 1 second intervals.

Unplug the harness from the main board to the power supply and plug in the AC. If the backlights come on and stay on with the main disconnected, your main is probably bad.