3GS Currently on 3.1.3 trying to go to 4.0

[still in school]

I just got a hold of a 3GS on 3.1.3 and I'm trying to upgrade it to 4.0 and unlock it. I changed my hosts file but iTunes is not letting me restore to 4.0. Is there a work around or do I HAVE to go to 4.1?

 

[eastercat]

If I'm not mistaken, try using pwnage. Even if you upgrade to 4.1, it'll keep your baseband from upgrading. FYI, baseband is what determines your ability to unlock.
Otherwise, click option+restore and itunes will bring up a directory where you choose your ipsw.

 

[infdarknite]

if you dont have the shsh blobs saved then you can only go to 4.1.. just use tinyumbrella to update without updating the baseband unless you dont need the unlock

 

[still in school]

Wirelessly posted (Mozilla/5.0 (iPhone; U; CPU iPhone OS 4_0 like Mac OS X; en-us) AppleWebKit/532.9 (KHTML, like Gecko) Version/4.0.5 Mobile/8A293 Safari/6531.22.7)

When I used tiny umbrella, it only saved blobs for 4.1

 

[nebo1ss]

I just got a hold of a 3GS on 3.1.3 and I'm trying to upgrade it to 4.0 and unlock it. I changed my hosts file but iTunes is not letting me restore to 4.0. Is there a work around or do I HAVE to go to 4.1?

Assuming you have access to a mac.
Download a copy of the 4.1 iphone software for the 3GS from the iphone wiki.
Download pwnage tool latest 4.1 from the DEV team blog link.
Run pwnage tool on the downloaded ipsw file to create a custom firmware.
Close pwnage tool and open itunes.
Do an option restore on Itunes and select the custom Ipsw.
it will update the firmware on your pone to 4.1 but the existing baseband which I assume is 5.12 will be untouched.
unlock with ultrasn0w from cydia.

 

[KentuckyHouse]

When I used tiny umbrella, it only saved blobs for 4.1

If I'm not mistaken, TU will only save the blobs for firmware that Apple is still signing. So, if you didn't grab your blobs for 4.0, 4.0.1, or 4.0.2 when they were still being signed, you can't get them now (unless there's a workaround that I missed...which is completely possible).

If that's the case, then you'll either have to stay on 3.1.3 and jb using jailbreakme.com or upgrade to 4.1 and jb using greenp0ison or limera1n.

 

[stockscalper]

Pwnage is the way to go.

 

[eastercat]

No workaround to get earlier SHSH blobs

If I'm not mistaken, TU will only save the blobs for firmware that Apple is still signing. So, if you didn't grab your blobs for 4.0, 4.0.1, or 4.0.2 when they were still being signed, you can't get them now (unless there's a workaround that I missed...which is completely possible).