Hi Alain,
I suppose you tried it the way they do it in this video: [https://youtu.be/hsop-mM1MZk?t=26s]
I wasn't able to do it that easy either. It took a little more effort. I placed the phone flat on my hand, screen up, bottom of the phone facing away from me. (After unlocking the blue locks. Note that there is a final click, so make sure the locks are all the way open.) Then with my index and middle finger I grabbed around the bottom of the phone where the blue locks are now (or somewhere you dont block the screen from sliding down) and pressed my other hand flat on the screen and slid the screen down.
[image|880442]
Don't apply too much pressure to the screen. Try to use as much surface of your palm as you can. If you have dry hands breathe onto the screen first or even use a rubber glove to have the necessary grip.
That did the trick for me. Hope that helps!
Best,
Jesko