Electric Mobility Mobility Electric Power Scooter Wheelchair. Heavy Duty "light won 39 work garage" Questions

won't go My nana's scooter has sat in my garage for about a year, but has been charged every week for at least over night. It is a Mercury M48. When you turn it on, all the electrics work

...won't move, but the left one does. Does one battery drive one wheel and one the other? The light indicates the battery is charged. It has sat in a garage for 7 years, but was working when it ...