Are you strange that the iPad Air won’t charge when the screen is black, but can be charged when the screen is on. Do you want to find the real reason and then fix it? Here’s the cause and solution.
USB current voltage meter can measure the charging current when it is charging with the screen on, as shown in picture 1-1.
When turn off the screen, iPad cannot be charged. USB voltage Charger Tester will displays 0mA, as shown in picture 1-2.
Now, we tear down the iPad Air and test it, we found that that the battery socket signals BATTERY_NTC and BATT_SWI_CONN are short circuit. The circuit diagram is shown in picture 1-3 and the material object of battery socket is shown in picture 1-4.
Use multimeter to measure the diode data of battery socket pin 2 BATT_NTC and pin 1 BATT_SWI_CONN. The two signals are short circuit and connected together. The data is 0, as shown in picture 1-5.
As there is no obvious abnormal on the surface of battery socket, we presume that the problem is caused by board short circuit. Use the burn-in battery to burn the short circuit. Connect the display and turn it on. Charge it by connecting to computer through a USB cable. When turn off the screen, iPad charging ability is recovered. The iPad charge function back to normal.