Jailbroken iPhone 4 stuck, and I have to recover to an older version

guilhermos said:

I just got an used iPhone 4 (4.2.1_8C148) from an american friend of mine. I live in Brazil so I don't get warranty, genius help, anything.

It is locked to At&t so last night I jailbroken it with redsn0w.
Reading a tutorial, I found a better way to unlock it with ultrasn0w. So I decided to restore it and do the jailbreak again, this time with ultrasn0w.

I restored it on the iPhone itself (not in iTunes), but it never turned on again. It gets stuck on the apple logo (for more than 6 hours!)

So the only way out I found was to recover on iTunes. But I heard it is not possible to unlock the 5.1 version yet. What should I do? iTunes is downloading the 5.1 version to start the recovery right now. I'm not really sure I should do it.

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It's seen like you don't know what you are doing so, why are you trying to jailbreak & unlock your phone?

Here is the fact.
1. Your phone as fw 4.2.1 which it has 02.10 baseband on it. Ultrasn0w can only work on Iphone 4 with 01.59 baseband.
2. Ultrasn0w is a unlocking tool, not jailbreaking tool.
3. "Reseting all content & setting" on device itself only work with non-jailbroken phone. Yours is and that the reason it hang.

Since you have destroyed your phone, the only option you have at this point is to restore it to the latest firmware which is 5.0.1. With this latest firmware, you have no option to unlock this phone including Gevey (turbo) sim. So, you now have a very nice ipod touch.

Put your phone into DFU mode and restore it with Itunes.

guilhermos said:

oh no, really?

Is it really unlockable?

Is there anyway I coud downgrade it?

Click to expand...

1. Check to see if you have SHSH blobs save for your phone. This will dictate whether you can downgrade your firmware or not.
2. Even you can downgrade your firmware, baseband can't be downgraded.

Basically, You are SOL for now because there is no option to unlock it for now.