Just got a new Roku Ultra the newest one. It worked great for a week or so than today when I switched input to the Roku it was making a high pitch noise through the Tv. The only way I could get it to stop was unplug the power and it went away. Turned it back on later that day and it did the same again. I tried different cables, different ports on Tv. It seems like it does it when you switch from the Roku back to another input than go back to the Roku is when it does it. I have never found a way to turn unit off. Is there a way to turn unit off.