Posted by Sam on December 08, 2014
These can have several different variations. Any yellow discoloration or ink like splotches are signs of stress marks. These are caused by too much pressure being applied to the LCD. Pressure could be caused by small pieces of glass that may have been left behind from your broken screen, and they adhere to your mid-frame. Pressure can also come from placing your finger directly on the back of the LCD screen. We suggest removing the LCD assembly, and thoroughly clean the metal frame of all glass, glue, and tape. There may be some sticky 3M tape or glue residue that you will need to remove before attempting to reinstall your new screen.
The red ones are 1.7mm long, the yellow one, 1.3mm, and the orange one, 1.2mm. You see, each of these screws is different.
Guess what happens if you install either red or yellow screws into the orange spot, since your eyesight isn’t good enough to notice a 0.1mm difference? The screw will cut into the PCB and break several 50 micron traces, yellow spot as shown in the picture above, or causing a blue screen error on the phone.