It may be necessary to change the battery if it's faulty or remove and insert it again if your mobile phone isn't responding.
Remove back cover
Turn the back of your mobile phone towards you. Take hold of the back cover and remove it.
Take hold of the bottom of the battery and remove it.
Place the battery in your mobile phone (top first), matching the battery contacts with the mobile phone contacts, and press the battery into place.
Replace back cover
Place the back cover on your mobile phone and press it into place.