I was handed a fully upgraded 3G to 4.2.1/05.15.04 today. I was able to downgrade it to 4.1 and then to 3.1.2 and found out it has saved SHSH blobs for 4.0 and 4.1.
I need to somehow downgrade the baseband to unlockable version.
Is there any way to "upgrade" to 4.0 in a way that it will reflash the baseband too?
In other words, I want to force iTunes to reflash the baseband.

Originally Posted by bimmerme

I was handed a fully upgraded 3G to 4.2.1/05.15.04 today. I was able to downgrade it to 4.1 and then to 3.1.2 and found out it has saved SHSH blobs for 4.0 and 4.1.
I need to somehow downgrade the baseband to unlockable version.
Is there any way to "upgrade" to 4.0 in a way that it will reflash the baseband too?
In other words, I want to force iTunes to reflash the baseband.

Unless the iPhone has baseband bootloader 5.8 - you cannot force a downgrade of baseband.

TinyUmbrella can check your baseband bootloader version. Only a fraction of a percent of the iPhone 3G that were manufactured have 5.8 baseband bootloader.


iTunes has *NOTHING* to do with this, the security model is built into the phone and enforced by the baseband bootloader and bootrom.