One of our two SKRT E-Scooter’s battery is charging but scooter not operating. Placed multi-meter on battery. Dial set in DCV at 200. Registered -43.6. When the charger is plugged in, the battery indicator shows fully charged. Once battery charger is unplugged, battery indicator shows red. Our other SKRT E-scooter, which works fine, registers -53.8 on the multi-meter . What could be the problem? Can anyone help with this?