You can skip steps: 13,14,15,16,17,18,19,20,22,23,24,25,29,30,31,32,33. Is not necessary too remove, screen, mother boar o battery. Starting at 34 step is enough just be carefull with a litle (plastic thing) under de mother board (step 36 photo 2) it's a bit triky to remove but you save a lot of time, you can hold the sreen with a rubber and a can (look iphone 5s teardown) It's not easy job, just do it if you don't mind to broke the phone. I did it with success with my wife's iphone that she didn't use it anymore.

You can skip step 9,10,11,12 it's much easer, just be sure not to open more than 90 degrees, I put the phone on a plastic box full of hot water for a few minutes and battery came out easily .