How to change LB/RB button of Xbox One Wireless Controller

First generation of Xbox One wireless controller has a mechanical design flaw at its LB/RB button.

At some point when you cannot press your LB/RB button or when you realize that your LB/RB button are loose, then you must disassemble that controller and replace the physical plastic button that act as a bridge between your finger and the tact switch.

Watch the video carefully.