I have seen similar issues regarding this matter. Lime others I bought this tv almost 2 years ago. I've had no issues with it and only used it lightly. Now all it keeps doing is turning off and on by itself in a loop. It shows the red tcl 4k screen for about 4min then turns off. It repeats this all day if I let it. I have tried holding the power button for 30 sec and nothing. I've tried un plugging and plugging it in after 20min. I've tried the reset button on the side, holding it and pushing it. Both ways just tur ed the TV off and it could tinied the same issue. I have no option to even go to any sort of menu for settings to view my model# or serial#. Whatz wrong with your product. It tells me to never buy a TCL or Roku product again.
Roku does not make TV's TCL does. Your problem is with them.
I'm sure they have a support line.