QUOTE(Mackiddo @ Sep 5 2011, 01:18 AM)
How can I upgrade my jailbroken 3GS from firmware 3.1.3 to 4.3.3 since now apple stop signing for the 4.3.3 ?
1. download official 4.3.3 ios for 3gs
2. make sure 4.3.3 shsh has been saved in cydia server...
-open cydia and check the status of saved shsh, u should see the ios version that cydia already saved in the server, make sure 4.3.3 is there
3. editing host file, required to restore 4.3.3 since apple only allow to restore latest ios only (4.3.5)
- go to C:\Windows\System32\drivers\etc\ and locate hosts file.
- open and edit the hosts file in Notepad.
- add the following lines to the very bottom of the hosts file:
74.208.105.171 gs.apple.com
- remove any other line that contains gs.apple.com
4. put your iphone4 into DFU Mode.
- open iTunes and connect the iPhone4 via USB.
- press and hold the Home button and the Sleep/Wake button at the same time.

- continue holding the both buttons for exact 10 seconds. Then release the Sleep/Wake.
- keep holding the Home button until iTunes pops up that it has found an iPhone4 in Recovery Mode.

5. hold Shift key in your keyboard and press Restore
6. select ios 4.3.3 file that u previously downloaded...