Firstly, test the iPad 5 with a 1503D+ DC power supply, when charge the iPad 5, the charge current reacts.
Disassemble the iPad 5 again, and then test the iPad 5 with a DC power supply, press the iPad power button, the boot current jumps from 250mA, which is abnormal.
As we know, for Apple product charging failure, if the boot current jumps from 230mA-280mA, mostly it's caused by iPad USB charging IC.
Log in to ZXW dongle to check iPad schematic diagram, we know that when we plug the Apple lightning cable to the iPad, J4600 tail plug flex cable will supply 5V USB power to Q1823, and then supply voltage to iPad power IC and iPad USB charge IC. If the charge current is too large, it will easy to damage the iPad charging IC.
Insert a Apple lightning cable to charge the iPad 5, now the iPad 5 can be charged successfully, the problem has been fixed!
Hope the above methods are helpful to you. If you have other methods, please leave a comment in the comments below.