Chosen Solution
My iPhone 6 plus was not holding a charge and I took it to the apple store and they changed the battery. The phone still is not holding a charge. It seems to have started happening after the last update.
I’m not aware of any battery issues with the latest iOS so that may just be a coincidence. What may be happening is that some modular element of the phone, for example a camera or sensor may be partially defective and drawing excess current, which would drain the battery quickly. This takes a while to troubleshoot because you have to run multi-hour tests to find out which one is causing this. Of course, it is also possible that the replacement battery isn’t good either. If you are comfortable, try the following: Fully charge the batteryClose all the appsTurn on max brightness and see how long the battery lastsThen open up your phone, disconnect the cameras, sensors (proximity/ambient light) & the Lightning port and do the same test. If you see the same result, then there is something wrong on the logic board itself. If you see a noticeable difference, then add one element at a time until you see what causes the drain.
