I struggled with this step, but eventually got it. Use LOTS of isopropyl alcohol, and soak the entire perimeter. Let it sit for 30 seconds after application, then heat it up, then pull with the clamp and rock back and forth. Reapply the alcohol and repeat until it works. Took me about 30 mins, but I eventually got it up just enough for the first pick. The iOpener is completely useless, I just used a shrink wrap gun and made sure to hold it 8-12 inches from the phone on the lowest heat setting.

This took me a very long time, but I found that I had to soak the adhesive with 91% isopropyl and let it sit for a minute, then scrub with a q-tip, then repeat until it was all cleaned up. My adhesive was very nasty and sticky, and none of it came off with tweezers. It took about 30 minutes total. Letting the alcohol soak in for a minute before scrubbing more was the key. Repeat over and over and it will eventually come off and be perfectly clean. Be sure not to bend any of the little metal tabs that are near the edge. It took probably 20 q-tips. I also used duct tape to clean up any little globs that got stuck in cracks, but only after the alcohol dried up.