Carefully insert a spudger underneath the battery at the same hight as the display connectors. You might need to reapply an iOpener or adhesive remover.

Be careful not to puncture the battery by prying too hard.

Pry up the battery using the spudger and cut the remaining adhesive with it.

Lift the battery with the spudger to ensure all the adhesive is loosened.

Place the plastic card under the center of the battery cell, and leave it there to prevent the adhesive from re-sealing.

Mind the Smart Connector cable.