If you are experiencing power and charging issues, carry out the following steps to reset your battery.
Important: It is not recommended to action this process on a regular basis. Only carry out the calibration once every few months, at most, if needed.
1. Let your phone's battery drain until it turns off completely.
2. Plug your phone into the charger, and without turning it on, let it charge until the on-screen indicator reads 100%.
3. Now, unplug and Power on your phone. If the battery indicator doesn't read 100%, put your phone back on charge until it reaches 100%.
4. Then, unplug your phone and restart it. If it doesn't read 100% battery, plug the charger back in until it reaches 100%. Repeat this cycle until your phone reads 100% battery when you start it up without it being plugged in.
5. Now, let your battery discharge all the way down to 0% and let your phone turn off again.
6. Finally, charge the battery completely to 100% one more time without interruption, and the battery percentage should be reset.
Note: If this does not help, there may be a technical issue with your battery.