Chris, All rechargable shavers have their battery(ies) soldered to the main circuit board inside the razor. In order to replace the battery(ies), you will need to disassemble the shaver by carefully removing the molded plastic cover(s) that hide the screws (which hold the shaver together). Sometimes located under the shaver head on certain Norelco models, others are under pressed in covers on the back and/or front.
Once you've done that, you have to be very careful not to dislodge any of the mechanical connections from the motor to the cutting heads. With the board exposed, you'll see the batteries, soldered to the circuit board via tabs that are heat staked to the batteries. Note which way the polarity (+ or -) are located on the board. Take a digital picture to make replacement and reassembly easier when you're putting everything back together.
Now with a pre-heated soldering iron, melt off the solder on the battery terminals and remove them quickly. Do not heat the tabs any longer than needed, so as to avoid possible damage to the circuit board. With the batteries removed, you might have to open up the thru-holes where the battery tabs go in, in order to get the new ones in place. Solder them into place and you're almost done.
Now reassemble the shaver and allow the shaver to recharge for at least 8 hours.
If you have any doubts about doing the repair yourself, you can have the shaver repaired by a service in Nebraska that specializes in replacement parts and service for all brands of electric shavers.
They usually can turn around a repair in a week from reciept.
Hope you find this Very Helpful and best regards!