Why mi ipad is always charging?

hello Charles,

I don't know what knowledge you rely on, but U2 (which is not present in this model) is not responsible for charging. Surely you are thinking about the NXP1610a3. The SMC hidden in the power management controller is responsible for charging. If, after disconnecting the cable, it still shows charging, it means that one of the separating resistors has shorted or the system itself has lost its mind. In the first case you need to find the culprit, in the second you need to rebuild the system (no backup) to cure the device. In extreme cases, PMC should be checked, although I do not recall a case where PMC is failed, but I'm sure that its can happen someday.

You have to disassemble the tablet and remove the motherboard again. With a multimeter in hand, trace the charging and power lines of the responsible devices. In fact, it's a fairly easy job. However, a bit of luck is needed due to the lack of reliable schematics.