The battery in my iPhone 5S was having trouble holding a charge ... or appeared so. The battery level percentage would jump drastically. One minute I'd have 37%, the next I'd get a low battery alert at 10%, followed quickly by my 5S just shutting down due to a dead battery. I'd plug it in and the battery percentage would immediately show 40 - 50%. Also, the battery, even after a full charge was erratic in holding a charge for any length of time.
The repair went well. Very easy directions on iFixIt.com, was glad I read through the directions before I started and glad I ordered the replacement battery with the tool kit. I ran into trouble with the batter adhesive strips for the original battery, and of course, as soon as I separated the battery adhesive strip tabs in two, both tabs immediately separated with the slightest amount of pressure. Not having the other tools that iFixIt sells, I resorted to a trimmed down credit card sized rewards card I no longer use and a quick hit from my wife's blow dryer (on low), which was enough to then use the trimmed down card and the flat tip of the spudger to gradually work the old battery out. That took most of my time for the replacement. I was left with the two adhesive strips on the casing of the phone, both of which easily pulled right out. Upon getting everything back together, I had the "white strips" down my display as well as some other not so nice display issues. The initial replacement took @ 30- 35 minutes. I then pulled the 5S back apart, ensuring the LCD cable was firmly in place before putting the cover plat back down over the three cables to the display. Hard stared the 5S and everything came up looking good. Battery was at 32% upon the hard restart am letting it work its way to 10% before I complete recharge it.
Thanks iFixIt ... my first stop for electronics repair.
Take your time and don't mix up the 8 screws that you will be taking out. These things are sooooo small that they are a challenge to work with, especially with the magnetized driver included in the tool kit.