The battery would sometimes just die completely and the phone wouldn't turn back on. Apple geniuses said I needed a new battery.
I was really worried after reading through the comments, but I had already bought the kit. So I forged ahead. I took heed of the warnings and marked not only which part of the process the screws came from, but also where each screw belonged since they vary even on the same part. The first adhesive came off fine. The second one started, but then broke. Using the spudger to pry up the battery was pretty easy at that point. I couldn't find the reassembly video, but reassembly was really easy. Just shove back in all the things you disconnected. Unfortunately, when I closed my phone, I must not have taken care to tuck all the display wires back in because the top sticks out a tiny bit. Going to go back in today and try to fix that. Otherwise, smashing success!! And I've never done this kind of thing in my life!!
Careful when closing the phone up again the display wires need to tuck away, otherwise you can't completely close the thing.