Dead batteries: Building Rollei E27 C

It works well with AC but batteries seems to be dead. Is there a way to rebuild them?
I try to open it and found a barrel shape batteries close to the capacitor and I have no idea about those batterr...

They/it's a NiCad battery. Here in the US Battery's + may have the ability.
Problem might be the availability of the cells themselves.

Otherwise search for NiCad rebuild services or electronics services In Germany.

I found the correct NiCad batteries for my Metz 402 battery pack on Ebay, they weren't expensive just over £12/15 euros including postage from Hong Kong If anything they'll have slightly better capacity than the old ones.

The measurements of the batteries are easy to find.

Ian