I cannot unscrew the Philips #000 screws in this step using iFixit's Philips #000 screwdriver. The screw does not even turn at all. I wonder about the screwdriver iFixit is using in the video - https://youtu.be/k_OpjhKAUCM?t=180 . Can we buy it ?

I faced the same issue. My 5S wouldn't open with the iSclack. Had to use the suction cup instead. Even then, I wrestled with it for a whole 30 minutes.. Apparently my 5S is one sticky beast.