[chb]

There cannot be waranty since there has been mechanical damage, even before the friend opened it.

I don't think mobile chicane mentioned anywhere "waranty". It's understood that it's "repair"

If damage has been done to the sensor socket. I would try running without sensor cable. I run mine without sensor cable with a LRP motor. For me the difference with & without sensing is only at start to 5mph, and even then, it is is barely noticeable.

Also, did you try the exact same programming on your friend's GM90 ?
often that sort of behaviour goes away with a RESET to factory defaults