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I have an iPhone 5s that battery was draining very fast, this happened after using cheap iPhone chargers. I decided to replace the U2 ic, after job done, phone started, booted to IOS and worked fine. I tried to charge this and when I put cable on the phone the screen got black and phone went completely dead. I replace the U2 chip again and no sigh of life. Can someone help me, why is this happened? Why is this worked only for some minutes? I burn any resistor? What parts need to test to find the problem? Thank you!
Did you actually check battery health using 3utools or coconut battery?
Try replacing the Q2 IC (4 PIN IC), right above it. You can harvest a good one from an old board, if you have one.
