This guide will show you how to remove the Dark Grey case that allows you access to the Motherboard.
To remove the back cover, use your thumb to press down on the center of case and slide it off.
Using a fingernail lift the battery out of the phone.
Slide the sim card out with your thumb.
To remove the back case first remove the four screws shown with a T5 Torx screwdriver
Using your fingernail lift up the side of the casing around the bottom of the phone to release all five of the clips.
Lift up towards the bottom and slide the case off.