Good to know for future, but in not much more you can buy used but working device :)

I had to open my Vivoactive HR because it wad died, what I saw it was water inside device :( Now I know that it is no super easy way to open this Garmin. 1st. you have to unglued plastic part where buttons sits 2nd. using this hole (buttons whole) you should gently push screen using something like screw (1) be careful with electric tapes (there are few) it is easy to broken (tear) using only a little force (2) there is only 1 screw on button board Maybe my photos will help anybody to repair this Garmin.

It is extremely hard to fix anything with this speakers, Plantronics service says it is not repairable, but... I can trot out that I have replaced one speaker from broken one my (green) with successful below picture how it looks like - very tiny :)