Downgrade iPhone from 4.3.5 to 4.3.3
Alec Jacobson
July 28, 2011
I upgraded to ios 4.3.4 and then 4.3.5 and finally wanted to go back to 4.3.3. At this point I tried to download the ipsw of 4.3.3 and restore with it via itunes. But I get the error: 
The iPhone could not be restored . This device isn’t eligible for the requested build.
  - Upgrade to 4.3.5 OOOOOPssss
 
  - Add 
74.208.10.249 gs.apple.com
 to the end of /private/etc/hosts 
  - Download the 4.3.3 ipsw
 
  - Use Pwnagetool in expert mode, giving it the 4.3.3 ipsw, this creates a custom ipsw
 
  - In Itunes option+restore using the custom ipsw
 
  - After that restore is done, RE-option+restore in iTunes, this time with the regular 4.3.3 ipsw