My ROKU remote all of sudden stopped working (no power on/off and no sound/mute) and coincidentally the battery icon in the top right hand corner kept popping up, very annoying because the batteries were brand new. I tried every single ROKU recommended fix....trust me.....EVERY ONE.
Then, I noticed that all of the problems appeared to be happening on both of my ROKU remotes (I have two smart TV's). The batteries I was using were Energizer AAA batteries which were NOT alkaline (ROKUS prohibts me from posting the type used). I switched them out with new Duracell Alkaline AAA' and voila....all issues resolved. I have no idea why the 'non alkaline' batteries should even be an issue because their voltage output is identical to the alkalines at 1.5v. In any event, both remotes now work perfectly and have been for three days now with no problems whatsoever.