Peel the orange adhesive strip labelled with a 3 off the battery.

Pull up on the orange adhesive strip to lift the battery out of its recess and swing it up to an upright position.

Although these adhesive tabs are supposed to make the battery removal easier, they may require some force. In case you're having trouble removing the battery, you can apply a heated iOpener to the center of the display to loosen the adhesive underneath.