If your motor wheel is making a grinding noise this can be one of 2 things. The first is a poor connection with the motor cable.
Please can you check the motor cable connection? You can do this by pulling apart the connector, checking that all the pins are straight and there is no visible damage.
Once you are happy there is no damage you can reconnect the cable, ensuring that both arrows meet, as pictured below. It is ESSENTIAL that the cable is plugged in firmly, with the arrows facing, right up to the indicator line.
If the motor cable connection is correctly seated it is likely we will need to replace your Handlebar bracket. Please contact us at firstname.lastname@example.org.