Right hand screw, boy what a pain. I felt that I would have to abandon the entire project after reaching so close to the end because I will end up stripping the screw. Finally I had to wiggle (gently) home button bracket back and forth after removing the left side screw to loosen the right hand screw a bit.

I agree with others that this step is hardest. I did this step in the end, i.e. after completing steps 20-24. This gives a better visibility and more room. I had to insert a small flat jewelers screw driver (very carefully and gently) underneath to complete step 19. I wish the plastic tool supplies to me was narrower at one end.