If you can stop a motor by hand it would seem the
speed controller for that motor is supplying a very
weak input to the motor.
If the motors are designed to run at the same speed
and not used for steering as it is a three wheeler
and steering is by front wheel, then another check
on the motor drive after the battery has been run
down/discharged and then charged fully allows you to stop
One drive wheel by hand it would point to a fault
other than duff batteries, unless you have a battery
for each wheel motor in which case it could be a faulty
battery.
Ned
