Two suggestions to modify this guide: up the difficulty and lose the video. You need to reshoot one showing how difficult is is to get the battery out of an old phone. The biggest problem was by far the adhesive holding the battery to the case. Maybe this came out easily when you did your first teardown, but for a 2-3 year phone these are now like hard glue. I had to use a combination of plastic card and spudger to remove it, and ended up bending the battery pretty severely. I was afraid it was going to burst into smoke and flames any time but fortunately no problem. It also seemed strange that the replacement kit did not include new adhesive strips. Is that because we don’t need them? I just left them out and the phone is working just fine. Definitely not a repair for beginners.
