I have the same problem also. Several e-bike service center don’t know the problem. They said xiaomi too complicated bike and no parts available in my country (jakarta - indonesia). Yesterday I went to another e-bike service center. The technician said he will check one by one. And just know he texted me, he found the problem. It is THE CONTROLLER. And now he is trying to replace with the one that he got in his store. Yes, he will try to modify or whatever to fit the new controller. I hope this will work.