"No signal" is just information. It doesn't necessarily mean anything is wrong.
For example, when I see that, it's usually because a device like a Blue Ray player or a Roku needs to be turned on/woken up, or I don't have the TV on the right input.
In the simplest case, you might want to press the home key on your Roku remote, or you can turn off the auto power savings: System -> Power -> Auto power savings
Banned but back. Because why not?
