I bought my m-850 in 2018. I have about 15 miles on it. The battery wouldn't hold a charge. In July of this year I "purchased" a new one. It took until 12-31*2019 to get it. Too bad it was a used and defective battery, Addmotor support staff were less than helpful. They took the money but now say I am not even in the system. Anyone know if the battery can be swapped out with a more reliable brand and how much would that cost?