What if Huawei smartphone suddenly loses its handwriting function?

According to the fault phenomenon, focus on checking the touch screen and its related control circuits. Disassemble the housing and visually inspect the touch screen. There is no obvious abnormality. Using a digital multimeter to check the resistance of 2kΩ, it is found that there are four pins (YT, XL, YB and XR from top to bottom) on the touch screen, in which the resistance between XL and XR pins is about 350Ω, which is basically normal, but the resistance between YT and YB pins is infinite, and the abnormal F should be about 600Ω). It is judged that the touch screen itself is defective. As there are no touch screens of the same model at hand, we take urgent measures to find touch screens with the same size but different interfaces. The method is to connect flying wires corresponding to YT, XL, YB and XR with enameled wires. After debugging, the touch screen function returned to normal, and the original fault was eliminated.