Adhesive Troubleshooting
Help for Battery Adhesive
These battery adhesive strips can be a little tricky. Here are a few videos that will help on how to do work with the strips.
Trouble install new battery adhesive strips when replacing iPhone battery. Watch this video:
https://www.youtube.com/watch?v=CrTDzkF6wvg
Plus here is a video on how to remove the old iPhone battery adhesive strips if it is stuck or broke. Using a little heat and scraping if necessary.
https://www.youtube.com/watch?v=Xthi6DOxe0s