iPhone Error 21 even in DFU mode

Discussion in 'Jailbreaks and iOS Hacks' started by smithgt, Oct 25, 2013.

  1. smithgt macrumors newbie

    Oct 25, 2013
    On my sons iPhone 4 we have experienced a problem where it would only power on when connected to the USB lead.

    Open opeing the back of the case I noticed that there was some water inside - we're assuming that a drink must have leaked in this bag and gone unnoticed.

    A drop of water was on the battery connector, so I disconnected the battery and put the phone in our airing cupboard overnight.

    The battery is now broken, as if I put it into my working iPhone 4, it wont power on.

    If I put my battery in my son's iPhone, then we get the iTunes and USB logo, and iTunes says restore phone. As soon as I remove the USB lead the device powers off immediately.

    If we do a standard Recovery Mode restore we get Error 21.

    If I put the phone into DFU Mode (which seems quite difficult), iTunes still attempts a recovery, some way through the first part, the PC beeps for a USB disconnect, but abaorts out with Error 21.

    I never get as far as the apple logo and percentage bar underneath.

    What else can I try? (The phone was on iOS7.02)

  2. darricksailo macrumors 601


    Dec 18, 2012
    Are you sure you're entering DFU mode properly? The screen should be completely black

    The issue could also be that it's a hardware failure as you mentioned water being inside the phone
  3. smithgt thread starter macrumors newbie

    Oct 25, 2013
    Yes - it's in DFU (with the blank screen)- it is a struggle to get it into this mode, but Windows did install extra drivers.

    When iTunes starts the recovery, the phone reboots, you see the Apple logo, and then Error 21 appears.

    Is it worth trying RedSnow or similar to rebuild the phone?
  4. TriJetHero macrumors 601


    Oct 13, 2010
    Easyway to get in DFU
    with USB connected
    Hold home +power until it turns of
    Keep holding both for another 3 sec
    Release power while holding home for another 10 sec

    You could manually try to download 7.03
    Then when in DFU hit SHIFT-restore in iTunes so you can select the downloaded IPSW
  5. thelatinist macrumors 603


    Aug 15, 2009
    Connecticut, USA
    Error 21 is usually caused by battery or battery connector issues, which fits well with your description of your initial problem. That you continue to get this error suggests that there continues to be a problem with the battery connector/connection. There are some sophisticated electronics connected to the battery, and it is not possible to be sure they are in working order just by visual inspection. I would guess that something in the power system is water damaged.

    Your best bet if you don't have AppleCare+ on the phone is probably an out-of-warranty replacement.
  6. jessatots macrumors newbie

    Aug 29, 2015
    Hi I have exactly 100% the same issue as this as well as what you and I have already tried. I am wondering if you ever got it fixed?

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