Great tip to boot the iPad before removing the adhesive from the battery. There are quite a few comments here about faulty batteries. Fortunately, mine worked just fine.
That is a great tip. There is plenty of space inside the case to lever out the battery without taking out all of the components. I laid the iPad on top of a large bean bag, heated for 3 minutes in the microwave. After 4-5 minutes, I was able to lever out the battery with the spudger and the credit cards. It came out after a few minutes of careful levering and cramming the credit cards under the battery. I unscrewed the earphone connector and carefully taped it back to the iPad housing with paint tape to have more room to maneuver.