I realize this is a Jan post . Also I too agree with Giradman on this link .
Sorta puts it like it is but in a more usable friendly guidelines. Ummmm
There is two things that I have seen and found on the screen /glass
setting that is often over looked in these tutorials .
The first thing and this is in order is the mastic that is applied . This mastic is what sets or bonds and helps as a moisture barrier , the digitizer/screen glass to the body of the I pad . In the old mastic may be a peice of glass or some mastic that was not thoroughly and completely cleaned off. Always take the old completely down till you see the body of I pad. And this is just the reason why. These tolerances are very close and if one thinks that the old mastic + the new will better the seal . Wrong answer. Completely clean .
The #2part which is a little aggravating is the bezel trim . Now you can re use the old one if you take care in the removal of the old but heck ,,,,
For a Coupla dollars more just buy one ....the problem that I have encountered with these rascals is they will want to twist slightly ,
When you install , leaving a wrinkle or pucker in the plastic and it will retain the memory of the crease or wrinkle. And it will go back together
But leave a raised or high place in the screen and is especially noticeable when viewing looking down the edge .
I have replaced 12 so far and not all mine I have devoloped a trick for the bezel and works well. If you apply a small amount of silicone (1eye dropper amount to each of the corners let it set for an 1 hr then install you have no worrys. Why the silicone ? Because it is not fully set in 1 hr and is set long enough to hold in place . And there is not that much used and should it need removed will be no more difficult than removing any way ...,.. Just a bunch of words. Best to Ya !