Chosen Solution
I went to an authorised service centre for battery replacement of my iPhone 6s as it drains too fast.. They told me that it couldn’t be replaced as there is some kind of issue with the motherboard (mlb he said). If there really is an issue with the motherboard then how does it work with my current battery?
Apple “Geniuses” are anything but. If they plugged it into their diagnostic tool and found some logic board issues, they will not attempt any repairs. Certain logic board issues can cause excessive battery drain and yet still allow the phone to function. Without knowing more about the specific issue your phone has and what the history of the device is, I can only suggest you either give us more info or have the phone looked at by a reputable shop that does micro-soldering repairs.
