@Lawyerjohn
If this is a Roku device plugged into a TV, verify that you are powering the Roku device from the power adaptor plugged into a wall (not into the back of your TV). If already plugged into the wall, try using another power adaptor. (cell phone charger). Just needs rating of 1A, 5V.
If this is an actual RokuTV, then most likely a power supply board issue or even power cord issue(less likely, though).
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