rear glass difficult to start removing, but went fine after that
Original battery, 2+ years old, had been through several overheat events (some app was abusing it from time to time). Capacity had grown limited, and in the last few weeks it had become flaky about reporting charge level, spontaneously changing from halfway charged to 1% charged, and then shutting down (due to thinking it had reached 0%) if I didn't restart it.
Getting started on removing the rear glass panel was difficult. Took a long time heating it, and required three hands: one to hold the aluminum midframe down, another to twist up on the suction cup and a third (my wife's) to get the pic started under one edge of the glass that had barely lifted.
Use plenty of heat. Residual adhesive on inner surface of rear glass can be removed with paint prep solvent; it didn't seem to harm the glass or any coatings that were on it. Per the instructions I peeled up the bulk of the adhesive from the aluminum midframe, but the surface was intricate and had numerous components, so I didn't attempt to clean any of the residual adhesive from there (there wasn't much anyway). In the end, the rear glass seems secure, and at worst, the case holds it all together anyway.