The top 2 screws (shown in orange and yellow) screw into the frame and/or stand-off screws. The 3 screws in the bottom triangle are sitting atop the motherboard millimeters above very tiny traces that can be breached if a longer screw is used, hence the name "long screw damage". This is often caused by in-experienced technicians and/or Do-It-Yourselfers who failed to accurately keep track of the screws.
When this type of damage is done, the only method to repair the phone is micro soldering with a microscope. It is very significant and often times can completely ruin the phone. The symptoms of this damage is often: blue screen on start up, red screen on boot, no backlight, no image on boot, phone still vibrates but no image on screen.Read More