Okay,
reboot your device by holding the Power key + Home key both.
until the apple logo disappear then release the keys and wait until you'll see the home screen.
if you're using PC, disable any antivirus, then try again.
(Updating the itunes to latest version is required)
Then do a new restore for your iOS.
updated to last version, and set it up as a new phone.
Then restore your backup.
(Note: Don't install any apps until you finished from your backup restoring )
Still no luck! I've tried updating itunes, re-backing up the 3GS and restoring again - didnt work. Then I set up as a new iPhone, the restored from backup, that didnt work, still stuck in the boot loop!
Still no luck! I've tried updating itunes, re-backing up the 3GS and restoring again - didnt work. Then I set up as a new iPhone, the restored from backup, that didnt work, still stuck in the boot loop!
Your backup has something conflict with the 4S settings !
Is your 3GS jailbroken?
if yes, then that's the problem.
what I suggest is using an app like JuicePhone on your mac to do a custom backup.
then use the itunes to add the photos from your custom backup.
and use the iCloud OR Google to add the contacts and everything else.
this way you'll have your data back without your saved settings that has been backed up from your 3GS, which will help you to solve this problem.