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Can't resolve itunes error 21 for restore.

iPhone 4s 16 GB Verizon model a1387

firstly the iPhone suffered a drop in water. took precautions to eliminate moisture placed it in bag of rice.

after 48hrs i tried turning it on. it would not turn on. i plugged it into my pc (windows 7 ultimate 64 bit version) and turned it on.

the phone was stuck on the apple logo screen i than initiated DFU mode to restore the phone. and well the phone was verifying software for the restore the iPhone screen went black and my PC made the sound as though the USB port was unplugged than the same sound occurred and the iPhone went back to the connect to iTunes screen and then the iTunes window popped up saying error 21 occurred.

I followed all support info on apple.com/support with no change in error code. 21

How i Troubleshooted:

1. i tried it on multiple computers and a mac, same code 21.

2. plugged the phone into wall and no charging symbol comes up just the plug into iTunes screen.

3. unplugged it from charger several hours later and attempt to turn on iPhone. it did not power up.

My thoughts:

I believe the battery may have gone bad from the incident. i did note there is a light char mark on sim tray but no charring on sim itself.

My question(s)

is there any other way to test if its battery or not?

does the general populous agree with my thoughts?

Any Ideas?

Answer this question I have this problem too

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7 Answers

mario, sounds like you are about right. the only thing that I would do different is, to clean the camera. Even so Rice is a great first aid, it will not remove any moisture that is retained in/under the connectors etc. This could lead to corrosion failure later on. Use this guide to see how to clean it, and of course, these guides to work on your phone. Once you cleaned everything, replace the battery. Re-evaluate from that point for any further damage. Hope this helps, good luck.

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Hmmm you say you tried DFU mode... did you try tinyunbrella? http://howtofixstuff.blogspot.ca/2013/09...

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If your phone was water damaged you have to change battery hopefully thats your problem. Error 21 is always to do with battery or battery connections. Replace battery if that doesn't work check battery connector on logic board might be damaged hopefully should sort it out had the same problem.

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Error 21 is always to do with battery or battery connectors that's great!! are you sure? someone said it could be the baseband chip?

I'd be very happy if it was just a battery problem

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Baseband error is 1 or -1 got a iphone 4s giving error 1 there was a small ic missing. Error 21 is battery or battery connections check properly hopefully you should sort it out

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yes there is another way of checking the battery n that is via multi meter set the multi meter to 20 dc and see that it should show 3.80 volts i.e 3.8 volts which is required for any iphone to restart

to check keep the red wire on (+ )and black wire (-) of the battery

to check which is postive and which is negative pole of the battery

google it

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Dear ,users Error (21)

i m apple user i had the same problem i tried many every steps what customer care people told me

but non of them worked ...

i even checked a solution on net

1) they said edit the host file in driver c/windows/system32/drivers/etc/host

2) reinstall itunes,disable anti software ,and etc non of them worked

than i realised that my iphone battery voltage must have fallen bellow 3.8 volts

so i removed the display under which battery was there and removed the battery and charged it with battery booster

(battery booster is a small machine which brings ur battery to minim volt

which is required to start ur phone )

to check the battery volt u have to use multimeter set it to 20 dc and check the battery volt

after the battery is reached to minim volt pack up ur phone

after wards download the software DRFone in ur computer and Run it

after installed

connect ur iphone to ur computer

click on more tools

and click on system recovery

and fall the procedure as they say

n hopefull ur iphone will restart with no data loss or anything just as normall

(incase u dont want to follow the procedure of battery boosting buy a new battery and remove the old battery and put the new on in ur iphone )

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mario will be eternally grateful.
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