Hello,Thanks for the question. My name is Dan.
Usually this is a Ysus issue (LGs are pretty notorious for this). But let's see if we can narrow it down for sure.
Looking inside the TV, there should be 3 large boards with heatsinks attached... and a few smaller ones. Turn the TV on and let is sit for 20 minutes (enough time for the TV to warm up). Then, touch the heatsinks (take care not to touch anything else).
Are any of the heatsinks cold? If so, which ones... on which board?Regards,Dan