Follow the below steps:-
1. Let the phone battery run out of charge, wait until it turns off because of low battery.
2. Charge the phone fully without turning on your phone.
3. Once it is fully charged, turn it on and leave it untouched for 30 minutes.
4. Again plug in the charger and allow it to charge for another 30 minutes, donít use it in between.
5. Once the battery is fully charged, unplug it and your battery is now calibrated.