Pry up the rear panel by pulling the dental pick counterclockwise in a quick motion. Apply force perpendicular to the plane of the display assembly. You may be afraid to go fast, but going slowly is more likely to bend the case.
Repeat the same procedure on the other side of the iPhone. Slide the dental pick completely into the square hole. You may need to wiggle the tool and apply a good amount of force to get it to go all the way.