Turret rotation and gun firing are separate problems. If the rebinding doesn't work (which is a great place to start), look at these:
Rotation/traverse: if you hear the turret traverse motor running, but no rotation, then the gear may not be aligned with the motor. Check that the motor and gear housing is fully seated and the turret ring gear is also fully seated. It sounds like they are failing to make contact.
Gun firing: I don't recall if the LED and the gun are wired in series or in parallel (I could be wrong...I take the LEDs out and replace them with a coax MG). FIrst, start with a freshly charged battery. A weak battery has enough juice to light the LED, but not run the gun's motor. Then, check the wire connections to the gun's motor and to the pin-plug in the upper hull. Make sure there aren't any broken wires in between them. If the LED is lighting up, then power and signal are going from the MFU. If the wiring is good, battery is fresh, and LED is lit, you may have either a bad gun motor (unlikely) or a bad MFU (possible).
Note: might be obvious, but just in case, do all tests with the smoker turned off and the volume silenced. I also recommend putting the lower hull on blocks so that the tracks aren't making contact. No fun testing something, accidentally hitting the wrong lever on the controller, and having the tank drive off.
At first i thought it may be the controller but since their is response from the tank.
