John I know its a bit late like a year too late. But it is right. You have to prize off the soft front pad to expose the two screws. After this, start at the bottom where the input connection is and again you have to split the main casing (not easy). This exposes the motor and batteries but unfortunately the battery lugs are soldered onto the underneath of the main board so you have to remove the board.After the splitting, at the top there is an alluminium shiny cover that holds the top blade assembly, so you gently lift it off the oblong lug. By the way, when replacing this alluminium piece it is has two tiny lugs at the back of it so make sure you locate these on the refitting.Remove the assemby by sliding it away from the main body. Now the board can be removed by lifting out the lead connection and moving the board slightly towards where this was,, this has to be done because the board is under little plastic lugs at the front. Now unsolder the battery and fit new ones. I got the new batteries (which are a new type and have to be first soldered together) from Strikealight company cost with postage approx £7.
Reverse the procedure and it works better than before and lasts longer under charge.
Mike M
Mike Morris
April 2010