Hi Doan,
For future reference, reviews are not the fastest way to get a hold of us. E-mail support directly at orders@outofdarts.com, or respond to any e-mail from us about your order.
A 9 volt battery may not have enough current to operate the motors. Please test the motor with a 3s LiPo (12.6v) and then e-mail support if it's still not functioning. We can provide a replacement at no cost.
