The black module simply lifts clear of the housing.

The clear lid has three clips on each side. Ease these up and lift the clear lid.

The PCB lifts clear of the black housing. It is a little reluctant but there are no hidden fasteners. I found it best to slid a flat blade screwdriver down the side of a battery and lever out.

Be careful not to apply pressure to the AC tabs, shown in the second picture on the right. They lift clear of the charger connection without assistance.