The headset of my partner stopped working. The battery doesn't hold charge anymore. Jabra doesn't provide replacement components. But the accu used (AHB472625PLT) is available from cellphone repair sites.
I found the "take it apart" instruction on IFIXIT. It's not hard, but you need a little courage.
On the shell that has the microphone, find the hinge that's on the opposite side of the on-off switch. Put a screwdriver just next to it, and pry the shell off its hinge. The "eye" on that side is made to allow it to be removed that way.
Once I received my replacement (12 € delivered from Germany), I'll solder it in, and test...