[Big Mac]

If someone responded to iTunes's constant nagging to download iOS 4.2.1 by choosing to download it and inadvertently upgraded his friend's jailbroken iPhone 3GS previously running 4.1 (new bootrom), would there be any way for that iPhone owner to downgrade back to 4.1? The friend had left the iPhone charging on the computer and realized upon seeing the new low quality Voice Memos app icon that his phone had horrendously been upgraded)

Note: The owner has his old SHSH blob stored by TinyUmbrella on Windows and also has his custom IPSW from Pwnage tool on his MBP, which he used to jailbreak and unlock 4.1.

1. Is it possible to downgrade to 4.1? (I've heard it's possible, having read about developers downgrading from 4.2 beta releases.)

2. Is it possible to downgrade to the previous baseband? (I'm starting to think the answer to this question is no.)

(Ok, I'll grant that it's not such a hypothetical situation. . . )

[ibook_steve]

Isn't there already a jailbreak for 4.2.1?

Steve

[exca1ibur]

If your SHSH is saved, yes you can downgrade. You just have to change your hosts file to point to the domain the SHSH is stored and restore like normal. Basebands however you can't downgrade. You have to preserve those when you upgrade or you are screwed

[Big Mac]

Okay, thank you exca1ibur - that's what I assumed, unfortunately.

There is a jailbreak for 4.2.1 but it's not clean yet. It currently requires a fake upgrade to the iPad's baseband that presents a lot of issues (like not being able to restore to stock firmware if absolutely necessary for Apple service), and that's not something my friend is comfortable with.

I hope they cleanly hack this new baseband soon.

If basebands can be upgraded by Apple why can't they be downgraded by hackers using the same technique? I'm surprised that can't be done.

My friend doesn't really even care much about jailbreaking - he just wants the unlock. It should be illegal to maintain a carrier lock on a phone when you're out of a contract.