I don’t get the glued battery complaint though. I’ve replaced the battery on 4 iPhones of 3 different models and the glue is just a sticky blob holding the battery in place. It was trivial to prize the battery off and press a new one into place.
The glue was so strong that you could not avoid damaging the battery when attempting to remove it.
You also could not safely remove the battery if it had started to bloat/become swollen.
This was, of course, about 10 years before pulltabs and adhesives that were solvent sensitive were used.