Tap and hold On/Off.

Tap Power off.

Tap OK.

Turn the back of your mobile phone towards you.
Take hold of the top right corner of the back cover and remove it.

Take hold of the bottom of the battery and remove it.

Wait 10-15 seconds.
Place the battery in your mobile phone (top first), matching the battery contacts with the contacts in your mobile phone, and press the battery into place.

Place the back cover on your mobile phone (bottom first) and press it until it clicks into place

Tap On/Off until your mobile phone is turned on.