Tschibo TCM hand-held rechargeable vacuum cleaner

I bought one of these in the Boston Tschibo several years ago (now closed down). I didn't think it was much cop in practice and therefore it was charged up less and less frequently. The other day I was clearing out cupboards and found the Tschibo. I've had it on charge for 24 hours, but there's no sign of life in it whatsoever. Although the transformer plug gets warm, the body of the vacuum cleaner remains stone cold. The green "charging" LED does come on, however.

Is the battery done for?

Any way to "resurrect" it?

Would these things have a "standard" rechargeable battery or one specific to Tschibo?

Any way to convert it to 12V direct, i.e. without a battery?

MM

The black and decker used c size nicads kind of daisy chained around the motor assembly as I recall, so all one needed were more modern batteries but with solder tags and it was fixed. Of course it was a rubbish cleaner!

Brian