NewToStream Power on/off is a TV function and not a Roku Ultra function. I assume the TV volume is also working? I don't know which you remote you have but try to repair the remote to the Roku Ultra. If you can not repair the remote try a factory reset of the Roku Ultra.
Make sure the Roku is powered on, then find the Reset button on the bottom or back of the device. The button may be tactile or a pinhole that requires a straightened paperclip. Press and hold the button for about 10 seconds. When the reset is complete, an indicator light or status LED will likely blink quickly.
I faced the same issue and nothing has helped me please give solution if anybody knows.
