This guide will teach you how to get to and install the plastic volume control button on the side of the phone.
To separate the battery from the phone, use your thumb to push in the button as shown.
Keep the unlock button pressed as you slide the battery away from the button.
Pull the battery away from the phone.
Use a T6 Torx screwdriver to remove the highlighted screws.
Carefully pry apart the two pieces, laying the back case to the side.
With the back case fully removed and out of the way, use your fingers to remove the volume button.