Sorry I have changed batteries in remote, rebooted my internet, switched it with another Roku on a different TV. The other one worked at both TVs but this Roku does not work at either of them. All I get is either a black screen or the bouncing ROKU letters. Please help
First, it never turns off. That power button on the remote is solely for the TV. If you have the Express connected to the TV's USB port use the supplied power adapter.
As was stated in the above reply, Roku stand-alone devices can not turn off. If the Roku is connected to the wall outlet then all I can suggest is that you probably bought a defective unit. It should still be under warranty and if so, you could contact Roku Customer Support here: https://support.roku.com/contactus, and return the unit to the store for a replacement. (https://support.roku.com/article/208757058)
~ Jordan