Ok Guys I am definitely !#^&@@ off right now.... but to the point.
Please Edit to this guide --> @Step 18:
First of all: Heat the for corners with your iOpener to lose the adhesive which sits in the corners.
Be very very gentle when you push down on the battery and try to put a little pressure onto or maybe into the headphone jack when you first encounter that the display gets lose, because the headphone-jack fits very well in the frame and holds on a little corner.
Only go around the whole display with a spudger when the adhesive is really warm to lose it when it doesn't come out as easy as you thought. Because otherwise you may face that the display to display-glass laminate gets damaged. That just happened to me at the upper display side... so to get a perfect new looking phone I have to replace that as well....EXPENSIVE :(
Hope this may help you guys.
but ... nevertheless ... thank you guys from IFixit for your continous effort to help people repairing there stuff - heads up :-)