I have a 50 inch TCL LED (LE50FHD3010M) that will power on and the display itself lights up dimly, as it does when no signal is present, but cannot get any display menus or anything. No input indication, channel numbers, startup logo image, etc.. TV remains on until around 5 minutes or so and turns off, which I believe it is supposed to do when left on with no input. Any ideas?