Caution — Photo 1 is slightly misleading — you don’t want to pry where the author is pointing with the spudger. Instead, carefully pry behind the connect, under the large black round rectangle until the connect pops out. Note the ribbon cable is held also with a small dollop of glue at the edge of the trackpad.
Like many others here, I completed the battery replacement by skipping steps 5-52 and instead removing the battery cells with the “cheese cutter” method. I made my cutter from 20# braided monofilament tied to two 4” wooden dowels (3/8” diameter). I carefully applied 97% isopropyl alcohol to the taut mono with a small artist’s brush. I took my sweet time cutting through the glue, but all in all not too difficult, just tedious. I was super careful and mindful of the fire and explosion hazard, and took necessary precautions. One thing to be careful of using the cheese cutter method is to be sure the mono is is really under the cell package and not just in front of it before sawing away. There are some tight spaces that make this tricky. Once the battery was out I used the iFixit acetone to clean up the glue leftover by carefully applying drops on the strips and letting capillary action take over. After waiting about five minutes, the glue strips could be picked up with the supplied tweezers.