Tv will fade to black after a few minutes

@christophe58813 if this is for the same TV as on here Screen fades to black after 5 minutes you should really keep those together sine the troubleshooting will be sequential. BY creating a new Question with each step it'll become difficult to determine what needs fixing.

Anyhow before probing, do this. Turn your TV off. Disconnect your power cable. Disconnect the right ribbon cable from the T-con board to the Panel. Reconnect the power cord and turn your TV on. Let us know what the results are. Then turn the TV off, disconnect the power cable, reconnect the Right ribbon cable, disconnect the Left cable, reconnect the power cord, turn the TV on. What are the results?

While you do that, I 'll see if I can mark your T-con board for test points. It's a Vizio so there will be no schematics ;-)