You have a bad COF IC on one of the panel boards, this is shutting down the power supply from over current, bad news is the set isn't repairable, you would need a new panel to fix the set, you won't find one anywhere.
You will need to unplug your TV from the power outlet and any power source for about 1 minute,then plug it back in. Check to see if the HDMI cable is properly connected.Or change it to a different socket. Do a factory reset.
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Apr 13, 2023 - Troubleshooting. 1 Check whether the lines on the screen are moving or permanent. 2 If the lines sway, check the input source (HDMI 1, Video, ...
Have you tested the backlights by removing the connector going to the main from power board, this will tell if the hot side of the power board is working and you will get backlights if they work?
This sound like an issue with the x-main board, if you unhook the power cable going from the power supply to the y-main board and you get VA and VS voltages there is about a 95% chance of the power board working ok, both the x and y main boards in this model set gave issues, one problem is going to be finding a board at a decent price, you can troubleshoot the board yourself, it's generally the mos-fet's that short, the ones that are attached to the heat sink. If you find some bad, replacement parts can be obtained from Mouser for a few bucks, they're easy to change with a soldering iron and some solder wick or sucker