iPhone XR cannot be activated and the customer said the phone has not been repaired before.
Troubleshooting
The phone can not be activated normally might be caused by the below four reasons
- The iOS system is too old (need to update the iOS to the latest version to have a try)
- The Baseband with the problem, can not get recognized
- The NFC chip is not recognized by the CPU chip
- The NAND series number does not match with the Wi-Fi and Bluetooth address
Let’s exclude the fault one by one.
Since the customer said the phone has not been repaired, so we can exclude the issue caused by the Wi-Fi & Bluetooth address not matching with the NAND series number.
And in the active status, we can the SN, IMEI, and MEID information, so the issue should not be caused by the baseband either.
By now, there are only two possible reasons left.
One is the low iOS system, and another is the NFC relative circuit.
Let’s restore it with iTunes first, after restoring, the phone still with activation problem. Then the only left suspicious part should be the NFC circuit.
Disassemble the phone and take out the motherboard, we found the phone seems to have been repaired before, and the NFC chip is not soldered very well.
Remove the NFC chip first, then measure the diode values on the PCB pads.
After measuring, we can find the PP_NFC_VREF pin relative diode value is abnormal.
The normal value should be infinite, and here the measured result is around 226.
This means this rail’s relative components must be with some problems, let’s just remove the capacitor C7534_S first. Then solder back the NFC chip.
After that, the PP_NFC_VREF rail diode value is back to normal, and the phone can be activated normally.
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