@Siciliano57, the Streambar, like almost all Roku devices, doesn't power off. The power button on its remote is strictly for the TV. If you can't get the remote to turn the TV off/on, try a different code. When it asks you if the music stopped, lie and go on to the next code. I've seen people say that they have problems with Samsung TVs, but I have a very new one and a very old one and I was able to get multiple Roku remotes to control both of them.
With the Streambar SE’s included non-voice remote, the SE would power on and off (LED light would show or turn off) but could not turn on or off my Samsung TV (no ARC or CEC). When I paired a Roku Stick voice remote, I could turn the TV on and off but the SE’s LED light would stay on.
Today I installed a regular Streambar with the included voice remote on another Samsung TV (via CEC) and both the TV and Streambar power on and off; the Streambar’s LED turns on and off.
I just realized my used streambar. I got won't turn off with a remote. It is not the remote that originally came with the streambar but it seems to control all the Roku commands. It just won't turn the streambar off. Am confused on how to proceed.
Your solution doesn't seem to have anything to do with the original poster's issue of not being able to turn off the streambar with the included remote
Roku do not have power commands, only one model of Roku ever did and that was the Roku 4. The power keys on Roku remotes are for TV power only. Sorry. You can't fix something that isn't broken.