[Renate]

You should be able to replace (or get someone to replace) the battery.
It's a thin one (in comparison to many batteries).
Normally batteries are known by their dimensions in mm and they are written on the case.
You can definitely find the right size out of China.
But normally the connector and the BMS (the little circuit board on the battery) can be custom.
It is possible to just replace the cell itself and reuse the BMS.
This is best left to a service person if your are unfamiliar with it.

Of course you could reuse it as a wall weather station/news/schedule.
You could just leave it plugged in.
A battery-ectomy is a little bit more complicated.