Screw Layout
On my laptop, Asus X555U, underneath it has 4 different types of screw: M2.5 x 8mm (2 of these), M2 x 9mm (4 of these), M2 x 12mm (4 of these) and last but not least, the single screw for the memory door is M2 x 5mm.
The memory door is the one not around the edge. (M2x5mm)
The two smaller, stubbier screws go in the corners on the screen hinge side of the laptop. (M2.5x8mm)
The four 9mm long screws go along the front edge of the laptop - if the left or right click on the trackpad stops working then unscrew a little until it works again. (M2x9mm)
The 4 longest screws go in the remaining places - along the sides and in the middle at the back.(M2x12mm)
I have a jpg of this if anyone needs it.
This has been collated from information on here, details on how-fixit.com, from taking the screws out of my latop after it had been repaired and returned and another post that I can no longer find!! I hope you find this useful.
I have not managed to find all of this information collated anywhere else on the internet!