In reply to Ridge:
> If it's anything like the other Garmins I've had there's no way to open them up without cutting them open, as they're a sealed unit.
Thanks for that. Interesting. On the reverse of the casing, there are 4 screws, one in each 'corner', clearly an unusual type of screw head, but probably there to dissuade chancers, or make it harder for a DIYer to get in , but maybe there is some hope of getting the case open, if there is a technicaian who might be interested/able
Photo: https://imgur.com/E3SLHW5
Mind you, I finally found out how to do a factory reset last night, and the watch seems to be behaving normally. Maybe I've sorted it or maybe I'm living on borrowed time!
Post edited at 14:47