Insert the plastic opening tool between the glass screen and the back cover so the curved end of the plastic opening tool is under the glass. Gently pry the back cover away from the glass screen.
Be sure to lift the entire display from the body and that you are not are lifting the glass from the display. You will need to reach down a little further for the correct removal.
Continue inserting the plastic opening tool around the whole device screen to completely separate the back cover from the glass screen.