iPhone  3GS
Instructions for  MAC 
Firmware  4.0  Downgrade to 3.1.3

Think you’ve made a mistake by upgrading your iPhone or iPod touch to the latest and greatest iPhone OS beta? iPhone OS 4.0 can be a little buggy and may not even work nicely with some applications, but that didn’t stop some from making the leap. Apple intended for this beta version of the iPhone OS to be strictly for developers and it shows. We're going to show you how to return your device back to OS 3.1.3 far away from those beta bugs.

We suggest reading this how-to in its entirety before proceeding with this process. We successfully downgraded our device from 4.0 to 3.1.2 on multiple iPhone 3GS models, but haven’t tried this process on an iPhone 3G or iPod touch.

 


 

1. Make sure you had your SHSH stored on Cydia before you updated (it should’ve displayed a message like the below screenshot for the firmware version that you want to restore to, before you upgraded).

 


 

Step 1: Open Command Prompt Windows aside (accessories/command prompt).

 

 

Step 2: Navigate to the following folder “C:\Windows\System32\drivers\etc”

 

 

Step 3: Now, look for the file name hosts and open it with Notepad

 

 

Step 4: Now, add the following line at the bottom of the file (if you have 74.208.105.171 gs.apple.com with some other number in the file, comment it out by adding  # in front of the line so it will be deactivated)

 

  • 74.208.10.249 gs.apple.com

 

 

Step 5: Now, click on File and select Save

 

Note: To double check if you updated the hosts file – go to command prompt  windows and type “ping gs.apple.com” you should get some thing like this ..

  • PINGING gs.apple.com [74.208.10.249]: 32 data bytes of data:
     

 

Step 6: Now, grab your iPhone, plug it in and lets put your iPhone into DFU mode.

  • Power off your iPhone
  • Hold both the power and home button together for exactly 10 seconds
  • Now, release the power buttom but, keep holding the home bottom for 15 to 20 may be till iTunes recognize your iPhone. (On DFU mode, you wouldn’t see anyicons on the screen. It will be blank on the screen)
  • Here, iTunes will alert your that “iTunes has detected an iPhone in recovery mode. You must restore it before it can be used.” Click okay

 

 

Step 7: Now, it time for us to restore the firmware – Hold down the “SHIFT” key and click on “Restore“.

 

 

Step 8: Select the Firmware and click Open to start the restore. (While its restoring, you should notice, the Command Windows which we have left at Step 7, should have the following message. “Successfully Wrote blob response“)

 

 

Step 9: That’s it! Now, you can just sit and relax and let the restore finish.

 

 

 

 

 

Error: If you get a 1600 Error, then try another computer and start the same process. You don't need to get the SHSH Blob because, we already have it.