Don't reuse the battery if it has been deformed or damaged, as doing so is a potential safety hazard. Replace it with a new battery.

Lift the battery up, away from the phone to remove it.

To install a replacement battery:

Remove any remaining adhesive from the battery well.

If you're using stretch release adhesive, apply them onto the battery. Otherwise, apply some double-sided tape, or pre-cut adhesive strips in the phone's battery well, being careful not to cover the charge port flex cable. Peel away any tape liners to expose the adhesive.

Temporarily re-connect the battery's connector to the motherboard socket. This ensures that the battery is properly positioned.

Lay the battery in place and press firmly.

Disconnect the battery connector from its motherboard socket and resume re-assembly.