This is the most dangerous step of all !!! You have to be VERY careful with the digitizer and screen ribbon cables when you bend it back to unscrew lock button. It is best to partially remove the screen so that you can get the cables out of the way (you've already disassembled most of the phone anyway, a little more won't hurt). The first time that I did this repair, I ended up damaging the cable and my screen was useless. Many people that I have talked to suggest the same thing!