The iPhone 7 Plus has unknown error 9, it can't be restored smoothly. After tried some simple software solutions, it still report unknown error 9. Now we need to fix it step by step in hardware aspect.
According to our experience, the iTunes unknown error 9 generally is caused by the disconnection between iPhone Nand flash to iPhone CPU or the iPhone CPU is virtual-welded.
Step 1
Disassemble the iPhone 7 Plus again, take off the iPhone motherboard, and then remove the iPhone Nand flash.
Step 2
Use digital multimeter to measure the resistance value of the iPhone Nand flash, the value tested is normal, which means the iPhone Nand flash has no problem; we need to check iPhone CPU.
Step 3
Carefully remove the iPhone CPU, and then reinstall it, then assemble the iPhone 7 Plus. Use iTunes to restore the iPhone 7 Plus again, the Apple logo appears normally, but after a while, the iTunes reports unknown error 56.
Why it's happening? As we know, the problem of the iPhone IC and NFC IC can cause this error 56. Firstly we suspected that there is faulty weld on the baseband, after re-welding it, restore it again, but the unknown error 56 still exist. We try to fix it by re-installing the NFC IC, but the problem is still there.
As we know, the faulty iPhone baseband usually will cause unknown error -1, and then faulty NFC IC usually will cause unknown error 56, so we still need to focus on the NFC IC.
Step 4
Open the ZXW Dongle to check iPhone 7P schematic diagram, we found there is big difference between 7th generation NFC and previous one, the front tip working condition is not from the main power supply, it converse by power supply tube.
Step 5
Is it the power supply tube problem? Use DC power supply to measure the output current for it, it doesn't has output current, now we confirmed that it's the problem of the iPhone power supply tube.
Remove the iPhone power supply tube, and then re-install it. Now measure it again, the current output is normal.
Step 6
Assemble the iPhone 7 Plus, use iTunes to restore it, now it succeed.
Press the power button, the iPhone 7 Plus is turned on smoothly. After entering the IOS systems, test the functions on iPhone , all works good, the iPhone 7 Plus has been fixed!
According to our experience, the iTunes unknown error 9 generally is caused by the disconnection between iPhone Nand flash to iPhone CPU or the iPhone CPU is virtual-welded.
Step 1
Disassemble the iPhone 7 Plus again, take off the iPhone motherboard, and then remove the iPhone Nand flash.
Step 2
Use digital multimeter to measure the resistance value of the iPhone Nand flash, the value tested is normal, which means the iPhone Nand flash has no problem; we need to check iPhone CPU.
Step 3
Carefully remove the iPhone CPU, and then reinstall it, then assemble the iPhone 7 Plus. Use iTunes to restore the iPhone 7 Plus again, the Apple logo appears normally, but after a while, the iTunes reports unknown error 56.
Why it's happening? As we know, the problem of the iPhone IC and NFC IC can cause this error 56. Firstly we suspected that there is faulty weld on the baseband, after re-welding it, restore it again, but the unknown error 56 still exist. We try to fix it by re-installing the NFC IC, but the problem is still there.
As we know, the faulty iPhone baseband usually will cause unknown error -1, and then faulty NFC IC usually will cause unknown error 56, so we still need to focus on the NFC IC.
Step 4
Open the ZXW Dongle to check iPhone 7P schematic diagram, we found there is big difference between 7th generation NFC and previous one, the front tip working condition is not from the main power supply, it converse by power supply tube.
Step 5
Is it the power supply tube problem? Use DC power supply to measure the output current for it, it doesn't has output current, now we confirmed that it's the problem of the iPhone power supply tube.
Remove the iPhone power supply tube, and then re-install it. Now measure it again, the current output is normal.
Step 6
Assemble the iPhone 7 Plus, use iTunes to restore it, now it succeed.
Press the power button, the iPhone 7 Plus is turned on smoothly. After entering the IOS systems, test the functions on iPhone , all works good, the iPhone 7 Plus has been fixed!
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