I accept you may not wish to go this far yourself but it might help others. Removing the mirror glass might reveal how the outer cover is clipped in place and the location and nature of lugs that need to be freed. Or it may give sight of, or access to ,the folding mirror motor and gears.
The glass normally has a frame on the back that clips onto the multidirectional adjuster cradle inside the mirror housing. It may need quite a firm pull to detach it ,and a firm push to reattach it. This can be scary as you fear breaking the glass - and indeed might do so. At your own risk