iPhone 5 Battery
iPhone 6 Battery
First adhesive (component side) broke during removal, but enough of it was hanging out to finish the job. 2nd strip (vol side) broke and snapped so far back I couldn't retrieve any part for pulling. HOWEVER, I proceeded with wedging a health care card, which is more flexible and thinner than credit card, and continued to push the adhesive from component side to edge of case. Once I have gotten enough adhesive bunched up and battery is showing signs of being lifted slightly, with health care card still in place, carefully swap a credit card and continue to leverage battery out slowly. (I did all of this without taking sceeen off, so be careful and do it at your own risk)
I also skipped steps 13-19 after reading the first comment.
Suction cup pictured here is the older version (with ring). I have one from my previous battery replacement on iPhone 5 and used that instead. The new one (gray with blue handle) kept on popping off. Overall, popping out screen was not as hard as it seems with these instructions, but do proceed with caution.