After disconnecting the battery from the chassis, charge it with the dedicated battery charger. It takes about 5 hours to fully charge the battery, and the indicator will change from red to blue when full. The two output wires of the battery are connected in parallel, so both heads can be used for charging and discharging (the charger has only one male), and the battery supports simultaneous charge and discharge

Wheel loosening solution

Solution: Re-tighten the screws in the figure above