That sounds like a frustrating problem to have with your WAREMA roller shutter. It's tough when you've already tried to fix it and the problem persists.
The fact that it worked for a few days after you changed the capacitor and then stopped again is very telling. It could be a faulty component in the motor itself, or it could be an issue with the remote control or receiver. Since you've already tried the batteries, the next logical step would be to get a professional opinion on the motor. Hopefully, you can get it working again soon!