Overview: The iPhone 3Gs screen replacement process will vary depending on what components are broken. The screen assembly is made up of 3 primary components that are the glass/digitizer, midframe, and LCD (see image below). You need to determine which of the components are broken and require replacement.
The LCD replacement is easier when compared to replacing the glass/digitizer. The LCD replacement only requires the removal of 6 screws to remove and replace the LCD.
The glass/digitizer replacement first requires the removal of the LCD, then you need to heat up the glass to remove the glass/digitizer off the midframe. The heat softens the adhesive so it can be removed more easily. Care need to be take not to overheat the ear piece speaker and proximity sensor during the replacement. Our iPhone 3Gs screen replacement video walks you through the process step by step.