We do not sell electric scooters so the scooter must have been purchased from another store, however, we will be glad to help you try to solve the problem.
After you installed the new controller did the scooter run, or has it not run ever since installing the new controller?
Have you tested the battery pack Voltage with the key switch on and throttle at full to see if the Voltage drops any when everything is on?
I bought an electric scooter from you about 3 years ago . Recently relaced the batteries for a 2nd time . It's endurance still was bad . Just replaced the controller , now it is totally dead . Batteries show 52 volts , when tested in compartment . I have no clue anymore . Do you have any answers .