So, just a small update on how things went.
The response I got from my bike shop was to send them a photo or video of what's wrong with the motor. But of course that would require opening the motor and voiding the warranty, a typical catch-22.
So I sent the motor to an independent repair shop in the UK. No major problems were found, and one plastic ring that has developed hairline fractures was replaced, but was found to not be a contributing factor to my problem. In other words, the motor wasn't the root cause.
Upon the reinstallation of the motor, I took the bike to the bike shop. They fixed a bent derailleur hanger and a worn out shifter cable. Magically my problem with the freespin has vanished -- the bike is fine now.
Just for the fun of it, I sent the photos of the broken parts to my seller. Their immediate responses was to ask me whether the warranty seal on the bike was broken because if so, Haibike's warranty is void. Well of course it was broken, the motor was taken apart entirely!
So the summary takeaway from the Haibike warranty is this:
- They want you to send the whole bike in (in my case: impossible)
- They want you to send in photos of the broken parts without breaking the warranty seal on the motor (in my case: impossible)
So there's that. At least I'm glad I now have a contact (albeit a few thousand kilometers away) that can fix motors.