Insert a Jimmy into the gap between the front and back cover assembly at the inside of the left controller handle.

To make sure you insert the Jimmy at the correct position where the clamps are located, you can use this photo.

Tilt the Jimmy upwards and push it into the gap between the covers at the same time to pry open the plastic clamp. You should hear a clack noise once the clamp pops open.

Once the clamp is completely open, the gap between the two controller covers should be about 2-3 mm wide.