Chosen Solution
hi, i have iPhone 6s and my iphone is shutdown unexpectedly. after the restart the battery is unkown in battery health setting, battery precentage jump to 1% and the iphone preformance slow down. i replaced 10 batteries, restore 10 times and nothing work. i sorry about my bad english :( thanks for helping John
You more than likely have a tristar U2 IC problem. You’ll need to find a repair shop that does micro soldering repair to replace it.
