A blinking yellow light is normal. The yellow light blinks while the Rover waits to pair, and a steady green light comes on once it has paired. The red light beside them only lights up when the Rover detects a system or sensor error, so normally it stays off.
Pairing. Press and hold the pair buttons on the Rover and the controller at the same time. Pairing is not automatic, so do this each time you switch on. If your own CircuitBlocks code is on the Rover, the controller will not connect until you put the original firmware back: see Coding the Mars Rover.
The controls. The controller's joystick drives the Rover over radio, and its knobs turn the arm, the claw and the camera tower. If a servo lags, turn its knob one click at a time.
If it drives on its own or steers the wrong way
Joystick caps. A cap pushed down onto the clear cover can cause slow driving, limited turning or a constant pull into a turn. Pull it gently upward.
Controller joints. Wheels that spin by themselves, or an arm that ignores the knobs, often point to the controller board. Reflow the joystick, knob and radio module pins, and check for solder bridges.
Backwards or swapped directions. The motor wires are reversed: with the batteries out, swap the two wires on each affected motor, in its connector or by resoldering.
If a servo will not centre, hums or keeps clicking
With the original firmware, the arm, claw and camera tower centre themselves every time you switch on. If they centre but ignore the controller, check the controller joints above. If a servo hums, clicks or cannot find its zero, in the build guide's zeroing step or later, work through My Mars Rover's servos or motors don't move, then ask us about the Rover Fix board.
If that does not help, message us here, or email [email protected] with your order number, photos of both sides of the Rover and controller boards, and a short video with the sound on.