@jdsteggar
The unpaired remote works now because it will use IR until it is paired, but this does demand line of sight.
Your Box Mini needs to be in direct line of sight when you first set it up, but once paired, it no longer needs this, will start operating over Bluetooth, and can be moved to the cabinet.
Given where you are now, besides resetting the remote, you also need to Factory Reset the Box Mini, out of the cabinet, to let it re-pair with the remote.
You may find that once the remote is paired properly, it will be able to control the TV power. If not, ensure that CEC is turned on on the TV. Their TV may know CEC by some fancy name, e.g. like Bravia Sync on Sonys; tell us the make and model of the TV, and we’ll tell you the name it uses for CEC.
Further, you may need to go into Settings/Remote on the Box Mini, and ensure the remote is set to control the TV as well as the Box.
Finally, there’s nothing wrong with using the HDMI ARC port for the Box Mini, except that this is the only port which will support a soundbar or AV system; so if there is any prospect at all that your grandparents may one day get one of these, best to choose a different HDMI input for the Box Mini now, so they don’t have to change from the one they are used to in the future.
*Longtime YouView box owner & broadband customer (was BT now EE), but only recently a full EETV subscriber*
