My TCL TV has the same issue...sound only but no picture. Tested all led strips and individual led in strips the all lit with tester. This eliminated back light problem. The main board replaced but no resolve. There are only two boards left to check or replace i.e. power board and icon. I could try replacing them both but you can't get these as new. You have buy them as used but no guarantee they are good working. Chances are these are taken out from a faulty TV and they are up for sale as spares. Chance to be taken with 50:50 keeping the finger crossed. If they both didn't work, then you end up returning to the seller to get your refund. It's just a lot of hassle. So what other choices are we left with.Umm! Owning a TCL TV is nightmare. Mind you as a new working device, the quality of picture is crisp, sharp and very pleasing only to find the bad side when broke and can't be fix easily.,🫤