Anyone Else Having Battery Problems with the Braun CoolTec Razor?

Hi everyone,

I'm hoping someone here might be able to help. I have an old Braun CoolTec electric razor I believe it's the CT2s model that's about 10 years old, and I'm looking to replace the battery because it got to the point that it only charges enough to give me 3 or 4 minutes tops of shaving time.

I've examined the device pretty thoroughly but can't seem to find any visible screws. The only access point I found is at the bottom where there is a little slot for a flat screwdriver to be inserted but when I insert one and try to use some force in any direction nothing really moves and it feels like the plastic around is going to brake. Has anyone ever opened one of these up and successfully swapped out the battery?

Any advice or pointers would be greatly appreciated. Thanks in advance!