Ok, thanks. There are a couple possibilities here. I'll do my best to give some insight into each. First, it could be your power supply (PSU). This circuit takes the line input... chops/rectifies/filters it, and sends it to the different circuits (3V, 5V, 24V, etc.). A fault here could very easily explain your symptoms... as this is the base for everything else. Repair here will vary depending on where you live, and on part availability, but usually runs $250-$450. Next, it could be the main board. This is your TV's main processor, so to speak. It controls the logic functions, and all I/O capabilities. So again, this could be your issue. Repair cost will be slightly more than the PSU, usually $100-$200 more. Finally, it could be the LCD panel itself (the screen). You're well aware of what part this is. Though, this would be far too expensive to replace... as it's the most expensive in your TV, by far. I wish I had a more definite answer on this one... but there really are a couple possibilities. You'll need a tech to determine for sure. If this information was helpful, please click "Accept"... it's the only way I get paid for my work. You can still post follow-up questions afterward.