Don't trust the controls on a heat plate. (Mine is a GE pancake griddle with a funky bi-metallic control knob that I sole from my wife's kitchen cupboard!) Aim an IR gun at the surface and measure it. Readjust as necessary, letting it stabilize. When I do smartphones, I use 100 deg C, laying the glass, face down, for 2 minutes. Possibly using 90 deg C, or less, will work better and do less harm. I don't think it matters if the glass rests directly on the heating plate, as long as you don't scratch the surrounding bezel - Gorilla glass is impossible to scratch. The toughest part of this is not being too aggressive, lifting too much, too fast. If it is not releasing with a thin blade (single edge razor), then heat it some more. Good luck with solvents; acetone can damage most plastics and alcohol may not be aggressive enough. I would stick with heat and be very patient. This is not rocket science but it is VERY delicate. Always, ALWAYS, be ready to buy a new display and don't forget the custom strip adhesive for the edges, either way. I've never had problems gluing back phones, but the larger surface area of a tablet may require reheating and clamping. Here's an idea: make a metallic frame that sits on the heat plate that only delivers heat to the outer edges of a tablet display say... 1/2" wide (12mm). Maybe even make it slide in two directions to custom adapt it to the size of the screen edge. Or Lego-like; build what you need. Just a crazy idea.
Of course, wear goggles and use heat insulating gloves to move the device to a towel or silicone pad for extraction. Be smart and safe.
I have noticed that the iPad Air 2-4 seem to do ok with the hot plate but the regular I models with with digitizer and lcd in two pieces are worrisome. I hurt the lcd in a couple of I - 6s . Used same temperature of 80 for each and took them off quickly.
The issue I have is sealing the new screen back. while a couple of tapes on the market are fair I found that cleaning the metal bezel trough thoroughly of any residue and wiping with acetone then after taping I put it back on the hot plate for a bit then use a lot of clamps. Now and then I still have some lifts. Some have recommended glue. To be fair to none who wants to open it again it seems glues might be problematic.
por dave bridenbaugh
@dave bridenbaugh tesa tape and primer