You're going to connect to the internal serial bus so that you, not the remote, can send commands. You'll add an Arduino to handle real-time communication between the Raspberry Pi Zero and the robot. Here are the steps:
Firstly, you need to disassemble the robot to get access to the main controller board. To do this, lay the robot face down so that you have access to the back. Remove the plate at the back by unscrewing the four screws that hold it in place. Now, at the top of the exposed board, you should see the main connector. The following image is a close-up photograph of the connector:
There are only two wires that you are interested in. The first is the black wire, which is the GND for the Robosapien system. The second is the white wire. This is the serial connection that controls the command for the Robosapien.
So, you're going to connect a wire to the black wire, but you need both ends of the black wire to stay connected to the...