ok, good. I was just out riding for 5km, got one 500 and one 530
...ohhh, and one other thing. When #500 occured it was clear that it is the motor. It made some rattling noise in the motor *. And then I tried walk assist just to see what's going on. And it didn't work correctly, it pushed with very little power and it staggered. And then it came, the deadly Error Code 500! And I had to walk a little. Tried power on/off a few times on the way. Suddenly after a while it worked again. And I got a #530, power on/off fixed that. Continued riding a km or so home, nothing happened. Strange this. But at least I know now that the newmotor is broken
(* heard that noise yesterday also but didn't catch it that time, thought something was looping in the fender or something, but now I know it was the motor)