I know I am not the only one who updated to iOS4, be it GM or Official, once it came out without thinking of how they were going to jailbreaking it. This is a way to go back to 3.1.2 (tested on GM, cannot confirm for official) so you can jailbreak using blackra1n and then update back to jailbroken iOS4. Is worked 100% on my old bootrom 3GS. Step 1 Go to /etc/hosts and add this entry "188.8.131.52 gs.apple.com" at the end of the document. You might need to change permissions to be able to do it. Step 2 Go to www.felixbruns.de/iPod/firmware/ and download the IPSW for 3.1.2 for your 3GS device. Step 3 Put your device in DFU mode and restore using the Alt+Click option you should already know about, pointing it to the 3.1.2 firmware. Once the restore is done, you will get an error 1015, don't worry about it. Step 4 Your device is now in recovery mode, DO NOT PUT IT BACK IN DFU, and restore again to 3.1.2 using Alt+Click, doing a normal restore. You will still get the same error 1015. Step 5 make it ra1n Step 6 Update to iOS4 Custom using Pwnage Tool 4.0.1 using other tutorials I did not come up with this thing, just made it simpler for people to use. This is the same method that was used to go back from 3.1.3 to 3.1.2 If anyone can confirm that it works for iOS4 Official, that would be great.