One of the easiest battery changes I’ve done.
All you need a good quality case back opener and a small screwdriver.
The case has a big indent so it’s easy to prise the case back off.
Loosen but don’t remove the screw then slide the bar off,careful it might spring off.
Fit new battery and reverse process,I got my battery from Amazon easy enough.
The case back snaps back in very easy.
I then gave the crystal a quick wipe over with polywatch,job done.
It is very easy way but the case is quite soft so care is still needed
Mine will need a change at some point in the near future.