I just purchased a 4G iPhone and was trying to downgrade my Iphone from 4.3.5 -> 4.3.3 using the following guide in order to have an untethered jailbreak:
http://www.limera1n.cc/2011/08/downgrade…

I was unable to downgrade and since then when ever I try to restore my iPhone using iTunes to any OS (5 or 4.3.5, both signed apple iOS's) I get any error that says "This device isn't eligible for the requested build." I followed other online guides to modify the host file to prevent iTunes from checking with Apple with no success. One time it work I received an error #1600.

Currently the iPhone appears to be stuck in restore mode (image of the USB connect to iTunes on the iPhone), and when ever I try to restore it to any OS I am unable to because of the error message above. I believe the error message is related to using redsnow, Apple now knows the phone has been tampered with but that is just a guess.

Right now the phone is useless... Any help at restoring the phone to any iOS would be much appreciated. My host file info is below:

Thanks,

##
# Host Database
#
# localhost is used to configure the loopback interface
# when the system is booting. Do not change this entry.
##
127.0.0.1 localhost
255.255.255.255 broadcasthost
::1 localhost
fe80::1%lo0 localhost

# Block Adobe Activation
127.0.0.1 activate.adobe.com
# 74.208.10.249 gs.apple.com
# 127.0.0.1 gs.apple.com