I have an RCA LED55C55R120Q 55" LED LCD tv. The screen went black.

I have an RCA LED55C55R120Q 55" LED LCD tv. The screen went black.

There is sound but no picture. No image in a dark room while holding a flashlight up. Tried replacing the main power board, the logic board and the led driver board and still nothing. Occasionally when it attempts to turn on, there is a quick flash..but only maybe 20 percent of the time. This quick flash that happens sometimes makes me question if the LED panel if actually the problem. Can someone help me out here.