Downgrade iOS 4.1 Beta to iOS 4 for iPhone 4, 3GS

How to downgrade from iPhone 4, iPhone 3GS, 3G from iOS 4.1 beta to iOS 4.0? this is the common question i am getting from iHackintosh readers. As you know Apple seeded iOS 4.1 beta for developers and it’s already leaked in the wild. So many people updated to beta build and now want to go back to iOS 4.0 lower for whatever reason, Following is the step by step guide for iPhone4, iPhone 3GS and 3G running on iOS 4.1 beta release.
Note : iOS 4.1 is still in beta and you needn’t to edit your host files for iPhone 3GS / iPhone 4 to bypass Apple signatures.

Instructions to Downgrade iOS 4.1 Beta

Step 1: Download and place iOS 4 on your desktop, now put your iPhone in DFU mode with following instructions.

• Connect your iPhone to your computer.
• Turn iPhone off.
• Hold power and home together for 10 seconds (exactly).
• Release power but keep holding home until the computers beeps (observed on a PC) as a USB device is recognized.
• A few seconds later iTunes should detect your iPhone.
• If the Restore Logo is present on the screen, you are in Recovery Mode, not DFU.

Step 2: Once your iPhone is in DFU mode following message will be appeared in iTunes.
Click on “OK” , Now hold Option key (Mac) and Shift Key (Windows) while clicking Restore in iTunes and browse the iOS 4 firmware for your iPhone. Now the restore process will take 10 – 15 minutes.
Step 3: After restore process if you encountered an error message like 1011, 1013, 1015, just ignore them(Actually the firmware is already successfully installed). To exit recovery mode download Recboot, once you finishes your download launch Recboot app and hit the “exit recovery mode” button.

• Recboot for Windows : http://bit.ly/9he64R (Requires .Net 4.0)
• Recboot for Mac : http://bit.ly/bBelW2

But if you encountered with error message like 1601, 1602, 1600 or anything else then try putting the iPhone into DFU mode and try again.