This step is very difficult and may require a third hand.

Pull the two halves apart at the bottom to detach the two latches that are holding the front and back panels together.

Start with one side of the controller (left or right).

Slide the spudger towards the end of the handles and pry the two halves apart. Do the same for the opposite side.

The white circular caps at the top of the controller will pop off by applying light force.

Pull the front and back panels apart to separate them and expose the inside of the controller.