It is especially important to keep track of your screws in this step for reassembly. Accidentally using the 3.25 mm screw or the 1.7 mm screw in the bottom right hole will result in significant damage to the logic board causing the phone to no longer boot properly.

Be careful not to over-tighten the screws. If they don't fit easily when you are securing them, they may be the wrong size—don't force them.