also, make sure you get the tiny rubber gasket that the prox sensor fits into snugly against the display. when i popped the sensor off, the gasket stayed behind, and i couldn't get the sensor to fit properly in the new display. i checked the old one again and saw the little rubber gasket that contours to the front camera lens opening on the display assembly. pulled it off with tweezers, and used it to get the prox sensor properly seated on the new display. i wish i'd taken a picture of it, but, well, my phone was in pieces in front of me.
thank you! this is a HUUUUGE note.
just completed a screen replacement. so far, so good. will keep an eye out for dead spots, stripes, lines, flickers, and all the other things that people mention. was hoping my non-functional touchID would magically return (it stopped working way back when i replaced the battery), but no luck. another great ifixit guide. only hiccup was not realizing right away that the proximity sensor has a little rubber bracket and diffusion screen that must be moved over to the new screen as well. but the comments helped a ton.