Try removing the HDMI cable from your TV that is connected to your Roku device. If using the Streaming Stick, remove the stick from the HDMI.
This should hopefully allow the TV to stop rebooting itself. If not, then try taking batteries out of Roku Remote in case there is a remote issue. May have to unplug TV again for a couple of min, but hopefully not. Then....
1. Change HDMI sources (if Roku was on HDMI 1, select HDMI 2).
2. Place the HDMI cable back into TV. Switch to HDMI 1.
3. If static noise reoccurs, try System Restart (Settings/System/Power/System Restart)
Feel free to post back with an update and any more details you can provide. Model number of the Roku device and the current OS build. (Settings/System
Roku Community Streaming Expert Just another Roku user... I am not a Roku employee. Insignia RokuTV, Ultra 4660, Premiere+ 3921, Express 4k+ 3941, Streambar 9102