Replace the batteries in the Sennheiser MTW 2

Hi, repair newbie here. I'd like to know if there are any guides/advice for replacing the batteries in the Sennheiser MTW 2.

I have a pair that I've owned since 2020 and they're still working, but they run out of charge in 10 minutes of use. It's likely the batteries were damaged when I used the wrong USB-C charger to charge them. I recently bought a new charging case for them hoping to fix the issue but it hasn't solved the problem.

As I said I'm very new to this and any advice would be greatly appreciated. I did find this video on YouTube but some comments referred to issues with the suggested replacement battery.

https://www.youtube.com/watch?v=hAvqtjCk...