Remove the card and again slide it under the top edge of the battery, near the center.

Be extremely careful to slide the card over the front-facing camera and headphone jack cables to avoid cutting them.

Slide the card in as far as it will go, breaking through as much of the adhesive as you can.

Lift up on the card to pry the second battery cell up from the rear case.

If there is significant resistance from the battery when you try to pry it up, reheat the adhesive with an iOpener and repeat the previous 3 steps to break apart the adhesive as necessary.