iPhones have many screws that are different sizes. Unlike many conventional boards that have space for dedicated screwholes that go all the way through the board, where screws will screw into the casing rather than the board itself: iPhones have screw grommets on the board itself. If you put a long screw into a grommet designed for a short screw, the screw will then make its way through the board. This damage will result in scraping way a layer of traces carrying signals or power lines important to functionality.
It is common for novice technicians to mix up screws and not know which screw goes into which hole. It is also common for novices to want to tighten the screws to feel like they did the job securely and properly. It is easy for technicians working at the pace required to keep up with customer expectations to lose screws, so this happens more commonly than people think.
Head over to our shipping page where you can start a mail-in repair to get your precious data recovered. Prices for this range from $300 to $650 depending on the significance of the damage.