Once the screen is warm to touch, apply a suction cup to the bottom edge of the phone.

If your screen is badly cracked, covering it with a layer of clear packing tape may allow the suction cup to adhere. Alternatively, very strong tape may be used instead of the suction cup. If all else fails, you can superglue the suction cup to the screen.

Lift the screen with the suction handle to create a small gap between the screen and the midframe.

Insert an opening pick in the gap between the midframe and the screen.

In case you only want to replace the display glass but not the LCD and digitizer you need to be especially carful during the next step. There's a small cable at the bottom right end of the LCD which is very fragile. Only slide with the very tip of your opening pick (about 1-2 mm).

Slide the opening pick to the bottom right corner of the screen to slice its adhesive. Leave the opening pick in place to prevent the adhesive from resealing.