I have a UN55KU6300FXZA that keeps cycling on and off. The stand by light will go out, backlight comes on for a second then stand by light comes back on and this happens constently. I have replaced the power supply board, the main board and even bought a new remote. TV is 3 years old and the very first week i got it turned off then off by itself. I didnt think anything of it at the time but about 6 months ago this happened and its not usable. There is no picture or sound when this happens. Do these tvs really only last 2 years or is there a fix?