How to Downgrade your iPhone 3GS 4.0.2 to 4.0.1

igor420

Download 4.0.1 .iPsw
http://appldnld.apple.com/iPhone4/061-8618.20100715.Zapn4/iPhone2,1_4.0.1_8A306_Restore.ipsw

Now Extract the file with Winrar to a folder on desktop.

open the buildmanifest.plist with the notepad, Search and replace all 8A306 with 8A400.

Now replace 8A306 with 8A400 from restore.plist to.

Open the original 4.0.2 that’s in C:documents and settingusername*application dataapple computeritunesiphone software updates*.* with winrar/zip.

Now replace all the 4.0.2 files in zip archive that you have open with all the above 4.0.1 files.

Now delete all the dmg files ending with 002, Leaving only 001 files.

Now save it.

Open host file and add the 74.208.10.249 gs.apple.com line.

Now Open itunes after putting your phone in dfu mode and let the itunes to restore.

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I have not done this as i am running 4.0.1..


http://www.theiloop.com/how-to-downgrade-your-iphone-3gs-4-0-2-to-4-0-1-firmwarewithout-shsh/

pjjk90

I already have a jailbroken iPhone on 4.0.1, would you be able to tell me how to reinstall 4.0.1 (I'm going to jailbreak it again after), I want to clean my iPhone as it is running very slow lately. I have looked for ages but have had no joy

Thanks

guil

that was supposed to be for the iphone 4 but i dunno if it works on the 3gs

guil

pjjk90 wrote: »

I already have a jailbroken iPhone on 4.0.1, would you be able to tell me how to reinstall 4.0.1 (I'm going to jailbreak it again after), I want to clean my iPhone as it is running very slow lately. I have looked for ages but have had no joy

Thanks

http://boards.ie/vbulletin/showpost.php?p=67716724&postcount=2

zuutroy

Didnt work for me. Still got the signing error despite modding the host file.

Kettle316

Do u have to have the iphone disconnected from the computer until the last step or does it have to be connected the whole time??

jamieh

Has anyone got it to work yet?

Friend of mine updated to 4.0.2 by accident.

brian2614

Is this for the 3gs or iphone 4 or both?

Spipov

so far, just the iphone 3gs. and i think for the new bootrom only. IIRC old bootrom you can restore just like a 3g.

Stuxnet

myth busted..

There is much discussion on many blogs about a potential means of downgrading iOS 4.0.2 to 4.0.1 by simply changing a couple values in the buildmanifest.plist and copying all of the images from 4.0.1 into 4.0.2 and then deleting the files ending with 002. Following all of this, perform a DFU restore and somehow you will be on 4.0.1.


There is a perfectly logical explanation for all of this and I will lay out exactly what is happening and explain why it is working for the folks that are the lucky ones.


Let me get this out first.

This is not a miracle, at least not in the sense you all hope for
SHSHs are STILL required for any iPhone 4, iPhone 3GS, iPad, iPod Touch 3G, and iPod Touch 2G (MC Model)
There is NO way around this... unfortunately this method included.
Let me start by explaining something very important. The buildmanifest is used by iTunes to build much of the TSS request that is used to obtain your SHSH for any given firmware revision. Unfortunately, the BuildNumber has no part to play in the request for SHSH. All that you ended up doing in following these directions is request 4.0.1 SHSH blobs. THAT IS ALL. Since every single one of you that got this to work changed your hosts file to point to Cydia, Cydia responded to the TSS request with an SHSH blob that was ALREADY "on-file". There was no magic. There was no miracle, apart from the lucky break that your device had been put on Cydia's SHSH request list at some time in the distant past.


That's it in a nutshell folks. There was no amazing technique for bypassing Apple's TSS. There was no amazing exploit that exists in DFU mode allowing for 4.0.2 -> 4.0.1 downgrading. It's simple; Cydia had your SHSH because at sometime in the past either:

Someone saved your SHSH with that device using TinyUmbrella and the default options
Someone restored that device with Cydia in the hosts pointing to gs.apple.com
Someone jailbroke the device and pressed 'Make my life easier'
That's it folks. Sorry to be a buzzkill but there was much confusion about this issue and many blog posts that simply didn't give the full story of what exactly was going on.

source

jamieh

So in a nutshell does this mean that it will or won't work?