I can see the TCL start screen for a split second

@tysalminen I am a bit confused by this:"Only thing is I DONT see any backlight when I shine a light on a dark spot for a minute". You can't see the backlight but should see the screen ie. Splashscreen, Menu or whatever else your screen should display. This" the TCL start screen for a split second" is usually a pretty good indication that it is your backlight array that has failed. If you can't see any shapes, silhouettes etc. then it is possible that this is a main board (worst case scenario a panel issue). Remove the back cover from your TV and post a picture of all of your boards. Arm yourself with a multimeter and let's figure out where we can measure the voltages for your back lights as well as the voltages controlled by your main board.

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I had a 55” TCL break 3 years ago. Can’t believe 3 years later & I see the same complaints…

I could see very faint shadows on my screen. You don’t have to be in a completely dark room to see this. But you def won't see it in a sunlit room. I don’t have a volt meter nor know how to read one. I am good w/replacing hardware/electronics. I took an educated guess that my problem was the cheap LED backlight strips. Fixed it & 3 years later this month and my tv is still running! Here is my long story - may not work to everyone. Good luck!

The sound is working but The screen is black.