Battery would go red-line from 100% in a matter of 4-5 hrs. With no apps or web sites open. All settings double checked in proper mode. This ifixit solution was the least dollar cost investment before replacing phone.
There has been enough said about the adhesive strip removal. But not enough videoed about the correct technique for positioning and applying the new adhesive strips to the battery. Some close up detailed video would be priceless. The strips are completely unforgiving and must be exactly positioned before laying them on to the battery. My battery is now successfully replaced. Case is Closed and screwed together tightly, bat. drained to less than 10%, and "Calibrated." Phone works fine, but Problem still exists. Must have a battery drainer somewhere internally, because both Apple and Att say that my settings are correct. Replacing phone thru my insurance for $99. Much cheaper than Apple or another pro.
Read the ENTIRE on line instruction as shown in the YouTube videos. Especially the colored picture of the positions of the four front cable assembly bracket screws and the two bat. connector cover screws. Make sure to map all six screws. Do not mix up the screws nor their positions. Keep them separated and properly labeled, It is very difficult to ID 1.2, 1.3, 1.6 and 1.7 mm. Screws once they are mixed together,
Pulling the case from the phone with a single suction cup and stopping the pull before the home button cable is yanked free is hardly possible without an ISclack tool. What happened was, the whole case came apart with a POP! Opening the phone just enough to be able to insert the plastic openning tool to help with this delicate step, requires more skill than is possible. A never opened phone will not come out of it's case gently.