I concur with Bryan’s post. The suction cup that was included with the toolkit that came with my battery wouldn’t hold to the screen when I pulled on it (the rubber was pretty soft, and the surface not smooth - not at all like the suction cup shown in the pictures of this guide). Fortunately I have a suction cup with a hook used typically for hanging things on the wall of a shower that held on quite tight that did the job - in fact, I had to use the point of the spudger to get under the edge of the suction cup to get it to release. I also used the zip tie trick someone else posted for making sure the screen didn’t open too far before disconnecting the home button cable, but it wasn’t necessary - I got the screen lifted with enough control that the cable was never in danger.