Use TinyUmbrella to Downgrade the iPhone IOS 4.3.1
As i already mentioned jailbreak and unlock of the IOS 4.3.1 is missing so till the newer or latest unlockers and Jailbreak comes out, you can still unlock and Jailbreak your device while downgrading it on IOS 4.3, 4.2.1 or any other previous older firmware. This is already mentioned how it will work. And Tinyumbrella is the tool to which will help you to completre the downgrade prociess of IOS 4.3.1
So first if you have upgraded to iPhone IOS 4.3.1, you have to follow some procedure which are menitoned here under in form of few steps.
1. First Download any of the older IOS firmware such as IOS 4.3, IOS 4.2.1 or IOS 4.1 or older.
2. Start iTunes on your PC or on MAC and connect your device with USB Datacable after turning it Off.
3. Connect your device with PC / MAC and put it on DFU mode (recovery Mode).
4. For this point, itunes will ask you to go for Update or Restore.
5. now here for PC users, go to file “HOSTS” while going through followign url in your windows “c:\windows\system32\drivers\etc\hosts” and open it and add following IP address : “18.104.22.168 gs.apple.com”
And for MAC users you can locate the file “Hosts” while going through following url “\etc\” through Go->Go to Folder. Open the Hosts file as “Text File” while right clicking it. and add the IP : “22.214.171.124 gs.apple.com”
6. after that click on restore and system will ask the firmware firle, which you have downloaded on the first step. locate it and go further with it.
7. System will restore it with the download firmware and rest of the thing will remain with itunes and it will complete the process of downgrading.
8. if you get error 1013, you have to Download Tinyumbrella because Tinyumbrella will get you out from errors and from recovery mode.
9. start Tinyumbrella and click on exit recovery mode on Tinyumbrella.
That’s it You are done.
Now to Jailbreak you can follow the Redsnow, Snowbreeze and Pwnaga Tool to Jailbreak your device and after that youy can follow the Ultrasnow to Unlock your device.
We suggest you to stick with IOS 4.3, which can be Jailbreak and Unlock as well. So downgrade to IOS 4.3