The existing battery on my phone was swelling. I thought that it would be a good idea to replace it with a new one.
Opening up and disconnects went fine. However, when I tried to remove the adhesive strips, they broke. I had to use a heating pad (did not have an iOpener) to attempt to soften and remove the battery and adhesive. It took a while to heat and pry the battery from the case. When I tried to apply the new adhesive to the battery the adhesive strips got soft and stretched. It was not a pretty job; but, I got the battery installed. Connecting the new battery was difficult since I did not align it properly when I attached it to the case.
1) Take the removal of the old adhesive strips very slowly.
2) If they break, give the iOpener (or other heating device) time to soften the old adhesive strips.
3) Do a dry run attachment (without the new adhesive strips) to see the correct alignment of the new battery in the case and connection.
4) Try to attach the new strips in a cool room so they do not soften. Be quick and deliberate in placing the adhesive strips.