When use servo in the first time, we need to remove the gear on the building block servo. Then, download the program to micro:bit. Next, turn on the power of the robot, wait for the building block servo to turn to the initial position. Then ,turn off the power. Finally, we need to install the gear on the building block servo.
In initial status, Left hand and right hand will put down, as shown below.
Servo 2 connect to S2 interface of PCB board.
Servo 1 connect to S1 interface of PCB board.