we are having the same problem with the volumn being stuck on 100. I believe the volumn control button is pressed in and can't turn off. We can turn it down on the tv but if we press any button at all it zooms back up to 100 by itself.
Thanks for the posts regarding the issue you are experiencing.
please set your Roku Remote again for TV controls. Navigate to Settings > Remotes & Devices > Remotes > [select your remote] > Set up remote for TV control. For more information about this setup process, visit our FAQ here: https://support.roku.com/article/115013019828.