@flashman what is your definition of pixelated light? If you darken the room and shine a flashlight at an angle agianst your LCD screen can you make out anything on the screen (Your TV has to be on and at a channel that normally display something;-) Open up the back and check the cables and individual boards for anything obvious like domed or leaking caps.
Just checked the Samsung Service Bulletins and your model shows up as potential SMPS failure due to SamHwa Cap causing MAIN BOARD EEPROM setting change. So you do need to check the boards. The caps in question are as follows
CM852,CM853,CM876,CM880,CB850,CS806,CM811,CM812,CM817,CM808
If unsure post some good pictures of the boards with your question. For that use [guide|21499|this guide]