Could I have found TSDZ2 error 30 (E30) cause?

[cj0]

The TSDZ2 is connected to a Kingmeter KM5S-LCD, showing error 30 (Communication error):

After half a minute it turns itself off.

After disassembling the TSDZ2 motor, I think that I have found the E30 cause: the black minus wire disconnected from the torque sensor:



Could that be the error 30 cause, or is there more?

Any suggestions how to re-solder the wire back to the torque sensor?

 

[cj0]

I ordered the "torque sensor small ring for TSDZ2 electric bicycle central mid motor" (replacement, I hope) part from pswpower.