How to Downgrade iPhone OS 3.1 to 3.0 for iPhone 2G 3G 3GS

Dev team already warned don’t upgrade to 3.1 and wait for next version of Pwnage Tool to preserve your baseband. Upgrading to 3.1 with Ultrasn0w installed will cause people to lose Ultrasn0w and will be unable to get it back. OS 3.1 contains a baseband update 5.11.04 BB for iPhone 3G and 3GS. The latest Modem Firmware

5.11.04 BB which is not down gradable. So if you accidentally updated your iPhone 2G, 3G or 3GS to OS 3.1 here is the handy guide for downgrading. Remember this will not downgrade your baseband only your firmware will be downgraded. It’s possible to downgrade OS however we strongly suggest you to carry on with OS 3.0 until Dev team releases Pwnage Tool.

Update for iPhone 3GS : So as of today, Apple has stopped signing 3.0 and 3.0.1 restore files. That means that if you have a 3GS iPhone you cannot restore any firmware other than 3.1. If you are happily jailbroken today and something goes wrong you are pretty much screwed. So this means you can’t downgrade even your OS from 3.1 to 3.0, Thanx to Saurik for making iPhone 3GS Downgrading possible. Follow the link below for our new guide.

Step 1: Make sure you have iTunes 8.2, Now connect your iPhone to your computer.

Step 2: 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 3: Once your iPhone is in DFU mode following message will be appeared in iTunes 8.2. Click on “OK” , Now hold Option key while clicking Restore in iTunes and browse the OS 3.0 firmware for your iPhone 2G, 3G, 3GS. Now the restore process will take 10 – 15 minutes.

Step 4: From here the guide is divided for iPhone 2G, 3G users and for iPhone 3GS users. iPhone 2G, 3G users simply RedSn0w your phone and you are fine, For iPhone 3GS user the way is little longer so be patience and follow the steps carefully.

• (For iPhone 2G and 3G only ) If you get error message like 1011, 1013, 1015, just ignore them(Actually the firmware 3.0 is already successfully installed). Simply launch RedSn0w and do the Jailbreaking Unlocking process again. Check our guides on Jailbreaking iPhone 2G here or Jailbreaking iPhone 3G here.

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.