iPad Pro No Touch Repair After Screen Replacement
The iPad Pro 12.9 is highly susceptible to no touch after screen replacement if the power source is not removed and/or disconnected. As a matter of best practices, the battery must be disconnected from this (and any other) device before moving to connectors. The two backlight filters are positioned very closely to the screw base and these filters carry VCC (Voltage Constant Current) even when the unit is powered off.
In the process of trying to connect, or even a sloppy disconnection, the display cables the VCC line shorts to GND and the sudden surge of current blows the small filter at the left end of the right FPC connector. This filter is directly related to touch
Upon closer inspection we can see the touch filter near the lcd and digitizer fpc connectors
Circled above we can see the touch filter responsible for the touch circuit, if damaged or blown the touch will not work, oftentimes caused by a short during the process of a screen replacement.
After replacement of the touch filter we have regained full functionality to the unit and we have a happy customer.