A new screen did not restore touch
The phone arrived after a hard drop and an attempted screen replacement. Because touch still failed, connector readings were checked rather than assuming a second display would solve it.
Four signal readings pointed below the top board
The missing lines included PMU_TO_SYSTEM_COLD_RESET_L, AP_TO_CAMPMU_RESET_L, BB_TO_MANY_GSM_BURST_IND and AP_TO_TOUCH_SCAN_CLK. Their routing led the investigation into the lower layer of the sandwich board.
Five interposer pads needed reconstruction
After separation, approximately five pads were found damaged: the four relevant signal connections and one ground. They were rebuilt to match the boardview reference readings before the lower board was reballed and the layers joined again.
The final test returned to the original complaint
Readings returned after the board work, but the decisive customer-facing test was touch response after reassembly. The final footage shows the phone responding again.
