Downgrade Iphone 2g/3g from OS4.1 to 3.1.2/4.0

Apple recently released its latest iphone firmware OS 4.1 . Many of us might have accidently upgraded it and might have done intentionally because of software issues.Unfortunately if you are using iphone 3gs and do not have your SHSH blob saved on Cydia server , nothing can be done at this point of time.But if you are using iphone 2g/3g and would like to downgrade it back to previous firmwares like 3.1.2 or 4.0 , you just have to follow the steps below :

Softwares needed :

1.Apple iTunes 9.2
2.Restore firmware 3.1.2 / Restore firmware 4.0 ( Google it , you'll find it easily or go to this link : http://www.iphonedownloadblog.com/iphone-downloads/ )
3.Blackrain by Geohot ( for jailbreaking on firmware 3.1.2 - again google it )
4.Recboot ( try google god again ;) )

Installation Steps:

Step 1: First thing ( probably the most importance one ) is to first trick apple to believe that you are validating your new firmware with it since Apple doesnt allow downgrading of firmwares anymore.For this, you need add a new entry in your host file ( usually located @ C:\WINDOWS\system32\drivers\etc ).Open the file called 'hosts' using notepad and add this :
74.208.10.249 gs.apple.com. This would point the itunes validation for firmware with Saurik's cydia server and it will grant you access to firmware downgrades.


Step 2: Now open itunes and enter DFU mode. If your not sure how to enter DFU mode , check my previous post on "how to enter recovery and DFU mode". Click SHIFT + Restore button on itunes and point to the firmware you want to install.

Step 3: After the process of installing the firmware completes, you'll see an error : 1015.


This error is fine and tells that your firmware has been downgraded , it just needs to be kicked out of the recovery mode. ( If dont get any error , you can skip step 4 ).

Step 4: Download and install Recboot. Open it and click 'Exit Recovery Mode'.


Be patient and wait for sometime while your iphone is being kicked out of recovery mode. Once the process is done, you'll see the apple logo with the usb cable pointing to it with a slidebar at the bottom.

Step 5: You have now successfully downgraded to previous firmware.If you downgraded it to 3.1.2 and would like to jailbreak or unlock it for any carrier, follow step 6.

Step 6: Download BlackRain and put it in the following folder ( this will avoid the asl.dll error ).

"C:\Program Files\Common Files\Apple\Apple Application Support\blackra1n.exe"

Open blackra1n.exe and click 'make it rain'. After your phone reboots , you'll have a jailbroken phone.

Note : You would not be able to unlock your phone since with OS 4.1 , your baseband is upgraded to 5.14.02 and as of now there is no way to unlock iphone on that baseband. Keep track of Geohot's ultrasn0w 1.1-2 @ repo666.iphone.com