Desolder the battery tabs and mask them off with electrical tape. You will need to use a fairly large soldering iron tip due to the side of the pads. You may well find you need to use an (ideally non-conductive) tool to lift the tabs clear.

Once all the tabs are clear, masked, remove all the phillips head screws from the board (several of which I have managed to lose by the time the photograph was taken).

Carefully begin lifting the circuit board and the adhesive paper underneath as evenly as possible from all sides. Waggle it a little to begin to loosen it but not too much.

Take care whilst lifting as there are three thermistors going down amongst the cells from the board. and you do not want to damage them.

When the board is free, place it to one side.