So... if you turn it on and drive 10 feet, what happens? Does it glitch at all, or does it just die?

What if you walk 2 feet behind it... can you drive it for an extended period of time that way? Is there any correlation between it stopping and the speed at which you were driving, the length of time you were driving, or the bumpiness of the surface? Or is it literally only distance?

It could be that the antenna on the receiver is damaged (not sure if it's external or not), or maybe the transmitter is faulty. I'd say call up Axial and see if they can help you diagnose it.