Downgrading, Brand new iPhone 4 - 4.0.2

[iYeow]

OK, so am i still screwed if I have a shsh file, but it's from a different phone? My iPhone 4 was running 4.0, but it was stolen last weekend. Naturally I got a new one, but, like everyone else the store gave me one with 4.0.2.

So can I downgrade with the shsh file from my old phone? Will that work?

No, it will not work, every Iphone has a unique ECID together with the Firmware creates a unique shsh blogs for that particular device and to be used for restore.

You can update to 4.1 and preserve your baseband if you update using tinyumbrella. Search and you'll find how to do it. If you updated to 4.1 already and updated your baseband to 2.10.4 on your iPhone 4 downgrade back to 4.0.2 NOW. When you downgrade on the iPhone 4 is will also downgrade your baseband, or at least it did with mine.

No, no, Baseband once upgraded cannot be downgraded.

[Ginger_Ale]

The Firmware Umbrella: TinyUmbrella with 4.1 Support

According to the tinyumbrella blog you CAN preserve your baseband while updating to 4.1 IF you have an iPhone 4.

Still, I am not gonna do it, I'm waiting for the jailbreak first

[korin125]

Indeed, when the new jailbreak comes out the process for unlockers will be to update to 4.1 (or 4.2) and preserve their baseband with tinyumbrella so you can unlock. Then you can jailbreak and install ultrasn0w. Should be very interesting.