Fifth generation of iPhone. Repair of this device is straightforward, and requires screwdrivers, prying tools, and patience. GSM/CDMA / 16, 32, or 64 GB / Black or White.

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I got an error saying unknown error occurs(code 51) when i'm restoring

Can someone help me out my i tried to restore my device but when it start to restoring its firmware an unkown pop up! I was manually restoring my device from ios 7.1.2 to 9.3.1

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Has the battery been changed in your iPhone 4S before? If yes then you may need to change to a higher quality battery as low quality batteries do not allow you to perform restores or upgrades via iTunes (maybe Over-The-Air too).

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I never change my battery before, i think my battery capacity is 1400mah


Yep, iPhone 4s batteries have a capacity of 1430MaH.

Error 51 indicates a hardware issue on your iPhone 4S.

Apparently having an non-OEM screen can cause this issue but I don't believe it.


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