Damaged Flex Cable
Please be careful with the flex cables on all parts. They are flexible but cannot be folded or been pressed with force. Folding or pressuring the flex cables will damage the structure, tin or lead inside. And that will break the connection inside and causing disruption or short in between components.
As a result the most common issues will occurred like, jumping or ghost touching on digitizer or LCD screens, proximity sensor not working, camera or mic not working and so on…
Below are some examples of badly folded flex cable.
Under the microscope