Jul 5, 2010 12:24 GMT  ·  By

A person writing on an iOS-jailbreak-focused forum claims to have been able to downgrade his iPhone 3GS from iOS 4 to version 3.1.3 of the iPhone software, using an older version of iTunes, DFU mode and an IPSW firmware bundle downloaded from the Internet.

Many users have recently reported bad device behavior after applying the iOS 4 on their “supported” devices, many of which have been anxiously awaiting for a proper guide explaining how to downgrade their firmware. The downgrade steps enumerated by Modmyi.com user timjs seem to have worked very well for this Apple customer, although Softpedia cannot confirm if the process described in his post is entirely recommendable.

The author of the post reveals he is the proud owner of an “iPhone 3GS purchased with 3.1.3, baseband 05.13.04 and mistakenly upgraded to 4.0, formerly jailbroken with Spirit and using Cydia and Rock for most apps.” He uses a Dell PC running Windows 7 64-bit.

After multiple failed attempts to get back on iOS 3.1.3 (presumably because some of the incompatibilities posed by iOS 4 on older-generation devices), timjs was able to find just the right formula by downloading the correct firmware bundle for his device, installing an older version of iTunes (9.1), running a program that temporarily modifies the PC boot process, and putting his phone into DFU mode for one final step - the restoration process using iTunes. Users may also need to modify the contents of a certain file, according to timjs’ post.

Although the how-to in question is extremely well detailed, those who’ve upgraded to iOS 4 and wish to revert to an older version of the software should not rush to follow the steps provided by forum user timjs. It takes just one error to brick a device, something which Apple’s warranty doesn’t cover. It may be wise to contact Apple themselves on the matter, although (to our knowledge) this kind of support is not provided by the company.

This article has a purely informational purpose and doesn’t, in any way, suggest that iOS device owners should follow the steps enumerated in the Modmyi guide. Softpedia does not encourage jailbreaking the iOS.

Update: article updated to include a link to the guide in question.