Merry Christmas! My nephew got a Gorgon for Christmas, and he and my brother spent hours assembling it from a kit. Unfortunately when they got it all put together, the car wouldn't go forward. The wheels will turn if you are holding the car up, but if you put it on the ground, nothing happens. Does anyone have any suggestions? The car will turn, but nothing else. They are nearly certain that they assembled it correctly. We'd love any suggestions. Thank you!!