@Momo-0
Need to cooperate with testing first to determine where the problem lies?
- Connect the LCD cable and use a multimeter to test the ground impedance of the two PINs shown in the figure below
- Disconnect the LCD cable and use the same method to test the ground impedance of two PINs
Test method: Set the multimeter to the diode position, connect the red probe to GND, and connect the black probe to the signal.