Bike shows errors and motor will not turn on

This week i bought a used qicycle. All seemed fine, but i wondered why the wattmeter always shows zero. The motor doesnt function at all. I tried to change  the firmware with the Chris app to the original one but that wasn't succesful either. I used DNS Changer as described in the post, put in the DNS IP,, paired with my google account, etc. If i tried to install the update the app allways shows "error on update 1". If  I use the original Mijia app and do a check, the check displays that everything is oK with the bike.

The display shows

LIN PIC: 003-013-000

MC : 005-019-000

BMS : 018-024-023

Firmware 1.6.613

I also tried to disconnect the rear Cable (torque sensor cable?) as showed in a Youtube Video, and booted the Bikecomputer sometimes again-no result.Here in Germany nobody could repair a qicycle, i would be glad if somebody could help with this issue and donate something to this person!.

First Idea was to change the controller board..but maybe the motor is broken...i don't know how to test ist. PLZ HELP ME !!!