When re-assembling, start off with replacing the 4.8 mm Philips screw first, then the 2.3 mm. This is to ensure there is no mix-up, and avoid rendering the LCD and digitizer useless.

Also make sure to put the long 4.8 mm Philips back in correctly when reassembling. This is the ground for the wi-fi antenna and is often the culprit if you are having bad wi-fi reception after reassembly.