Why will a 12v power supply be connected to the display when you have to weld a 5v jumper it, you are to provide the screen how much voltage, if welding a 5v jumper can only provide 5v power, more than will burn the power supply circuit behind, you first check whether the power supply is correct, in addition to the CPU box circuit below the four groups of bare leakage test points, you can use a multimeter to test the leftmost group of 3.3v Test points, first test whether the short circuit and then test the voltage is normal, in addition to the back of the screen is two light-emitting led, please observe the led near the CPU is flashing, flashing that is the normal work of the system program