Funkční návod pro downgrade 3GS koupený po 40tém týdnu, právě se mi to po celodenním testováním povedlo

1. download and save to desktop (don't unzip) 3.1.2 firmware from internet. i think i used felixbruns or something
2. right click notepad, run as admin, open computer>c:>windows>system32>drivers>etc>hosts add this entry with NO # in front of it 74.208.105.171 gs.apple.com
3. put iphone in DFU mode not recovery, computer should beep notifying you usb device connected but screen should be black not itnes connect screen. google for exact directions.
4. from itunes with phone connected and in DFU, shift click restore and select 3.1.2 firmware, error meassage at end 1015, thats fine, phone is now in recovery mode with itunes connect screen, shift click restore again with 3.1.2 firmware error 1015 again, everything is ok
5. close itunes with iphone still connected
6. run redsnow, browse to firmware select yes for new model and "run tethered boot only" do not install cydia
7. wait for phone to boot now you have working service through ATT and 3.1.2 firmware. ok to update carrier settings.
8. shut down phone and reboot now your back to itunes connect screen
9. run blackrain and install cydia
10. start downloading sick apps!!!!!
Enjoy!