This is my second time replacing the battery on my 5S. The first time went well though the phone never held charge for very long, but it at least wasn’t dying at 30% anymore. My kids used it for almost 3 more years. Now on replacing again I’m having problems. When charging for the first time it started out at 7% and charged very unevenly — seemed to hang at 34% and 77% but finally said 100%. Then in trying to use some apps to drain the battery again the battery readings were jumping all over the map and we were getting blue screens and random reboots and the phone heating up. I am trying to restore the phone and that completed, but restoring a backup isn’t working in time before it reboots. We did not remove the display in replacing the battery, so we didn’t mess up those long screws, but it’s possible we damaged that cable. More worried there’s an issue with the battery, given the heating up. Powered off for now, not sure what to try next!
I had watched the video and I tried to work the strip around the sides, but couldn't get it to go without worrying it would tear on something. I just pulled up at an angle, slowly and steadily, and they both came out fine, like the instructions say.
It may help to position the suction cup off-center and pull up one corner first.