According to information on Galaxus, I contacted GR Rapido Service GmbH / info@rapido-service.ch for a warranty claim (rotating brush no longer rotates). You should get an answer there.
If it's really just the cable of the power supply unit, I would probably try to repair it (soldering or with clamps).
Otherwise, you can also try to use an equivalent power supply unit (same voltage+current+plug), but finding a suitable one will probably be rather difficult...