Embarrassing question really, How do I gain access to the battery to charge it. I have managed to get the side panel off but cannot see how to remove the black box cover to gain access. Do I have to remove the seat? Again, embarrassing but I cant see how to remove the seat, no obvious release clips/levers, I think it slides onto a locating stud at the front end of the seat but cant see how the rear of the seat is held down . . . . screws? Any help much appreciated