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How to restore iPhone 3gs with error code 21

I have an Iphone 3GS. I replaced the battery and digitizer. When I plug in to Itunes the Iphone wants to "restore", but I recieve an error code 21, and it will not "restore.


Any suggestions?


Thank you,


Peter

iPhone 3GS, iOS 5

Posted on Jun 13, 2012 5:30 PM

Reply
9 replies

Jun 14, 2012 12:02 AM in response to pscott47

Why did the iPhone need a restore in the first place? It shouldn't have needed one just because of a battery and digitizer. I've seen a number of bad batteries that were supposedly brand new. So that could be the cause as well. You might also double check the battery and make sure it says 4.51 Whr on it. If it says 4.26 it is a 3G battery which isn't compatible.


One way to quickly know if it's a bad battery is if you unplug the iPhone from a charger and it immediately shuts off. That means the phone isn't charging or pulling anything from the battery itself. You could technically put the phone together without a battery and it would bootloop with the Apple Logo.


Jonathan

Jun 14, 2012 4:39 PM in response to fccrepair

Jonathan,

Thank you for your suggestions. Yes, I made the mistake of getting the wrong battery, but now having the correct battery I still have the problem of "error 21".

The Iphone is in a "restore loop" each time it's connected to ITunes it wants to restore, but when it's done "error 21" pops up..?


Any other suggestions? It seems like there should be an easy fix to bypass this error message and restore the Iphone...?


Thank you,


Peter

Jun 14, 2012 5:09 PM in response to pscott47

Peter,


In the past, I have had some devices show that error but I was able to simply hard reset the device and it booted fine.


Was the phone jailbroken before? Also, I would make sure you are attempting the restore in DFU mode versus Recovery mode. It sounds like it is having a conflict with the baseband which is why the device is not allowing itself to boot. You might also try using TinyUmbrella to fix recovery.


If you continue having issues, let me know. Also let me know if you are using PC or Mac and which OS you are running.


Let me know how it goes! If it doesn't work I may have a few other tricks up my sleeve.


Jonathan

Jun 14, 2012 5:32 PM in response to fccrepair

Jonathan,

I'm using a Mac OSX 10.7.4.

The Iphone 3GS is not Jailbroken.

I've attempted to use both the Recovery mode and DFU mode to restore the device.. same result.

It may very well be having a conflict with the Baseband, but I have no idea what that is..?

I can give TinyUmbrella a try.. Is there any other way where I don't need to download a program to fix it?


Thank you,


Peter

Jun 15, 2012 2:06 PM in response to pscott47

Peter,


Thanks for narrowing it down! The baseband is the modem firmware. Usually if iTunes errors out at the end of a restore it is due to a conflict with the baseband. I am almost positive that TinyUmbrella would solve your problem.


At this point, the easiest thing to try without downloading any additional programs would be to try a different computer. Of course, if you haven't tried restarting your computer and using a different USB port you might try that.



Let me know!


Jonathan

Sep 19, 2012 8:53 AM in response to fccrepair

hi

i was given an iphone3gs recently and it was jailbroken and unlocked, i accidently restored it on itunes and now it wont activate and when i try to restore it it comes up with error 21, my dad said he had upgraded it as well once beofe and he got it reversed at a phone repair shop, cani fix this problem at home or would i need to take it to a shop,

thx

How to restore iPhone 3gs with error code 21

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