Resolution not supported. Change resolution of the external device
I have had my roku device for almost a month. Just yesterday my TV stopped recognizing it. For some reason my TV is saying the resolution of roku device is not supported and that I need to change to resolution to the external device. However I can't do that if Roku won't open up on my TV. I have tried the reset button and that does nothing. I am pretty annoyed because it doesn't seem to be a way to fix this and I have wasted my money on this device. There is no one to talk to in customer service due to covid so now I'm stuck and no pleased at all.
Re: Resolution not supported. Change resolution of the external device
Is it a stick or a console (little box)? Does the light on the device flash when you press a button on the remote? Do you hear a sound when you press a button on the remote?
Assuming you can still control it, you can try blindly changing the resolution:
Press Home on the remote 3 or 4 times
Press Up, Right, and then Down 3 times
Press Right, Down, and then OK
That should change the resolution to something else. Assuming it was set to "Auto detect" that should set it to 720p and hopefully display something on your TV. Once you get something to display you can try the other resolutions.
If you still can't get any display try a different HDMI input on your TV and/or a different HDMI cable.