3GS (old boot) 3.1.3 (5.12.01) Spirit JB + Unlocked >>> 4.x.x with unlock

[hemen_kap]

Hi,

I purchased an iphone 3GS from craigslist long back and it has served me well so far. The specs are as follows

3GS - old boot rom
Firmware - 3.1.3
Baseband - 5.12.01
Jailbroken - Spirit
Unlocked - Yes (ultrasnow)
Carrier - I use it with ATT Sim
SHSH Blobs on cydia - 3.1, 3.1.2, 3.1.3, 4.0, 4.0.1, 4.0.2, 4.1, 4.2.1+, 4.2b3

It was already unlocked when i bought it and works like a charm.

Now I have been wanting to upgrade to the 4.x.x ios but I want it to be unlocked (even if i use it with ATT)

I have read the guides section and I understand the process to be as follows

1. Downgrade to 3.1.2 (guide)
2. Run blackra1n and jailbreak 3.1.2
3. Edit host file back to normal
4. Use snowbreeze to JB on 4.0 (Guide)
5. Unlock using Ultrasnow (Guide)


I am technically sound and am active on the wii hacking scene, but iphone is totally new to me, and with all these tools and so many dependencies, it is getting a bit confusing.

I would appreciate if more experienced members can answer few questions.

1. Do you foresee any challenges I may run into with the above approach?
2. Do i need any special version of itunes to do all this stuff ?
3. Is there a chance of getting my iphone unusable ? Is there a fool proof way to still make the phone work if i screw something real bad (I am ok if I lose the JB and Unlock features then)

appreciate the community members and hope they will guide me in this learning process.

Regards,
HK

[iYeow]

restore to custom firmware of 4.2.1 created by pwnage tools of 4.2 to preserve your baseband. if you don't have a mac, google search from the net, use redsnow to put into dfu mode, run iTunes to restore to cfw of 4.2.1

[hemen_kap]

Thanks. any guide that explains the concepts and steps?

is this compatible with the current state (i.e. Spirit JB) ? I read a couple of guides and they mention spirit is unsupported, so i did not want to take any chances.

[iYeow]

That is the guide, there are lots of guide from iClarified - Apple News and Tutorials
spirit and jailbreakme don't work at 4.2.1
redsnow 0.9.6 rc8 browse to stock 4.2.1, check only dfu box. once dfu is done ,run iTunes :shift + restore to cfw of 4.2.1 (if u are using windows)

[Techyrock]

You can also use snow breeze 2.2 for windows to make a custom 4.2.1 firmware preserving your baseband,its important to preserve your current baseband because if updated then it will not be supported by ultrasn0w until now or later