Did the same and the battery never came back …    

I vaguely remember you can buy spares cells and rebuilt the battery by yourself. Of course it implies still having the original battery. Also, I don't know if there is any electronics inside the battery. If not, maybe just adding cells and make them fit inside the battery space would be enough. But I've been through a lot of trouble replacing battery cells in B&O equipment, namely Beo6, so I wouldn't be surprised if doing all by the book would still not work.

I have one that I took apart and another I’ve yet to try.  What company or factory could event look at replacing these cells?  There is quite a bit of electronics and monitoring in the battery itself. I am willing to try and if successful would have a spare for someone if replacing the cells is possible.  Let me know