Place your hands on the phone as shown in picture. Slightly pull the tab away from the phone with your thumb.
Lift the battery up from the phone as shown. Replace with a new battery if the old battery has become worn out.
Remove the rubbers with a tweezers.
Remove the 4 screws as shown in the picture
laid it on a side, use the tool to separate the front and back.
Put the tool in friction tabs and force down to open the cover as shown in the picture
Pop it open using your thumbs