Chosen Solution
Hi, I have an iPhone 6 that was draining its battery very quickly. I first changed the battery in hope this would fix the problem, but it still drained very quickly. I then replaced the Tristar IC. This fixed the battery drain issue. Although now when I power off the phone, it stays off for about 5 seconds then powers on by itself. I also notice that when I attach a charged battery, the phone powers on without pressing the power button. I am unsure if this was a problem before changing the tristar IC. No cable plugged in to the phone, power button flex is functioning fine, iPhone 6 running iOS 11.4. Any help would be greatly appreciated.
After removing the charging IC (U1401), reballing and re-soldering back onto the motherboard. Now the phone is working perfectly. The phone no longer reboots after I power it off. I hope this will help anyone else with the same problem. I guess replacing this with a new component would work also.
Try disconnecting the power button flex to see if the problem persists. A bad flex could be “starting” the phone on it’s own.
