From my limited experience, iOpener is a really cool thing if nothing else is available, but if possible, hair dryer will do the job much, much better. Though, with iOpener is much harder to do something wrong...

I completed the calibration on my P8 Pro, worked fine. There is one point however for anyone attempting it: Use proper, quality cable! My phone wasn't recognized as a device after I connected it with some random cable from my drawer (works fine for charging the phone), after I used something better it worked like a charm.

Such a simple and dumb thing, but it can make a difference between failure and success.