Dev team already warned don’t upgrade to 3.1.3 and wait for next version of Pwnage Tool to preserve your baseband. Upgrading to 3.1.3 with Ultrasn0w/Blacksn0w installed will cause people to lose their unlock and will be unable (for the time being) to get it back. OS 3.1.3 contains a baseband update 05.12.01 BB for iPhone 3G and 3GS. The latest Modem Firmware 05.12.01 BB 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 3.1.3 until Dev team update Pwnage Tool or redsn0w Tool.
Update for iPhone 3GS : So as of today, Apple has stopped signing 3.1.2 restore files. That means that if you have a 3GS iPhone you cannot restore any firmware other than 3.1.3 But in case you was wise/lucky enough to save your Cydia SHSH files on Saurik server follow the link below for iHackintosh guide.
Step by Step Guide to Downgrade iPhone 2G and 3G
Step 1: Make sure you have latest iTunes installed, Now connect your iPhone to your computer.
Step 2: Put your iPhone 2G/3G 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. Click on “OK” , Now hold Option key while clicking Restore in iTunes and browse the OS 3.1.2 or below firmware for your iPhone 2G, 3G. Now the restore process will take 10 – 15 minutes.
Step 4: If you encountered an 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 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.
Disclaimer : This process is universal and tested several times though we are not responsible for and damage (if any) so use it at your own risk. If you like our work then consider to digg the story and help us by spreading the word.
Stay tuned with us for your daily dose of iPhone news, you can follow us on twitter via @ihackinjosh You can also subscribe to our daily free e-mail news letter and keep your self updated with the latest of iPhone community.