Try to find the power & current specifications of the battery from Dusan's answer on this website:
Maybe you'll be lucky? Good luck!

https://www.akkushop-schweiz.ch/akkus...

Unfortunately, we cannot offer a replacement battery at the moment, as none of our suppliers offer it as a spare part. The batteries are not the same for this and Badoo model, both are Li-Ion, but they have different capacity 3.7V/1000mAh for Badoo, and 3.7V/2200mAh for Wavemaster KidzAudio Music Box.