My phone was shutting off at random intervals regardless of the displayed battery level.
Opening the phone was the easy part! Getting the adhesive strips out was a rather challenging and time consuming part. I broke the strips initially and couldn't get the process started. Once I got a good hold of the strips, they came out rather easily. The ifixit videos were very helpful there. Putting the phone back together proved even more challenging. The display and digitizer connections were rather difficult to reattach. I had to assemble and resemble the phone multiple times to get the connections correct. Each time there were lines on the display and the digitizer did not respond to touch input. Once I got it correct my phone was almost like new! I feel like the new battery doesn't quite last as long as the original battery did when it was brand new, but at least my phone is reliable and will last through a full day on a single charge again! I call that a win!
Make sure there is no debris on any of the connectors for the display connectors. This may have caused some of my issues during reassembly ..