Roku TV line and players keeps restarting or will not stay on

The checks in more detail

which you hold with a straightened paper clip for about twelve seconds until the status indicator glows dimly, then release; Roku Pro Series TVs have a Roku-remote-shaped button next to the power button, and holding it and power together for at least five seconds resets the TV; TVs with no reset button reset when you hold the power button ten seconds. For a streaming player, check the status light: no light means no power, white light with no picture means check the TV input, a solid red light means the device is too hot and should be unplugged to cool,

and a flashing red light means it is not getting enough power, so plug it into a wall outlet. Use the original power adapter, reconnect the cable, try another outlet and avoid power strips. If you power the player from the TV's USB port, use the original cable, try another port, and if the TV cannot supply enough power use a 5V 1A adaptor at the wall. Roku's auto power savings setting can turn a player off. For a TV that restarts, unplug all devices and test.

A useful test before any repair is to unplug every cable except power for ten minutes, then plug the Roku in alone. If it starts, add devices back one at a time until it fails; the last one added is the cause. Note the order so you can tell Roku support exactly what you tried. Keep the box and a photo of the label showing the model and serial number, since warranty and service requests ask for both, and the label is hard to read once the TV is on a wall mount.