Remove the watch strap.
Using a screwdriver (tri point screwdriver Y00), unscrew 4 bolts.
Open the back cover.
Using a screwdriver (Phillips 1.5 mm PH000), unscrew 2 bolts in the PCB.
Disconnect connectors on the PCB.
Remove the PCB.
Disconnect a connector on the PCB.
Separate PCB from the cover.