Matt had some great suggestions. First, I always advise my customer that there is a risk of breaking the glass more when it’s cracked like this. First thing is to heat the back up really good to loosen the adhesive. Then I would suggest starting at the top. Normally I start at the bottom but I want to avoid the crack. Keep the back really hot and take you time. The card was a good idea. Ether way, I wouldn’t have high hope for getting this back glass off in one piece. Of course, in person I could see the crack a lot better.