This is likely some components on the power board wearing out but just to be sure please try this:
-unplug the tv POWER cord from the wall outlet.
-press and hold the power button on the tv (not remote) for 20 seconds and release.
-plug in the tv power cord and turn on.
-Test for normal operation.
If that does not work then unfortunately there is not going to be any easy reset/fix. The tv needs diagnosis, parts, and service.
As an experienced technician, theoretically I could help you with the repairs but if you do not have the needed skills and tools then having it repaired by a local shop is your best option. I can help you with that too, just provide your zip code.
Despite the bad news, I hope you appreciate the answer that I provided so far. If you need more help or don't understand something use the REPLY option.
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