Remove the 2 screws from the black metal part which covers the mute switch. Also remove the 1 screw, which is attached to the silver metal piece.

We remove the black metal part to release the mute switch and volume buttons, which are attached to another silver metal piece.

Note for reinstallation: After screwing back the metal pieces, perform a quick check that the buttons work properly. For the mute button make sure that the exterior and interior switches are sliding together. For the volume buttons, check that the buttons make a clicking noise. If the screws are too tight, then the volume buttons can be stuck.

Note: If the volume buttons were stuck, just loosening the screw on the silver metal piece may fix the problem. The whole flex assembly may not need to be replaced.