jailbroken 3GS iOS upgrade + unlock

[PedroCheco]

Hi, I've got this one running now:
3GS new bootrom
iOS 4.2.1 jailbroken using redsn0w and unlocked with ultrasn0w
currently with 05.13.04 BB downgraded from the iPad one.

Could you guide me how to upgrade to iOS 5.1.1? I'm not familiar with differences re this BB. I want the unlock too. What I did so far was saving SHSH blobs with Tinyumbrella. Thanks!

[cyb3rduck]

Just a warning here, the 3GS with new bootrom is sensitive to incorrect baseband upgrades. DO NOT install the iPad baseband it will brick your phone's radio. THIS IS IRREVERSIBLE or at the very least extremely difficult to correct! You will need to preserve your baseband when upgrading, if you perform the upgrade blindly in iTunes it WILL irreversibly update your baseband preventing a downgrade later.

So instead of using iTunes to perform the update, use this method instead:

This explains how to upgrade the iPhone to iOS 5.1.1 - the crucial thing is you make a NO_BB IPSW to restore to. You can use Redsn0w for this.
Update to iOS 5.1.1 - Preserve Baseband (Mac & Win) | Absinthe Jailbreak.com

Once this is done, run TinyUmbrella or use redsn0w to preserve your SHSH blobs.

EDIT: Please remember to open Cydia, allow the file system preparation to run uninterrupted. Then open Cydia again and tap Search and look for Ultrasn0w (note the zero in Ultrasn0w) and install this to allow the unlock to work. After the iPhone reboots its preserved baseband should remain unlocked.

[PedroCheco]

Thanks cyb3rduck. I'm not planning to upgrade to the iPad BB. I got this phone from eBay with the 06.15.00 BB on it and only recently found out about that cool downgrade option.

I created my custom no BB 5.1.1 IPSW using latest redsn0w (0.9.14b2). But when I put the phone in Pwned DFU and tried to restore it through iTunes, i got an error in iTunes during restoring (the screen on the phone stayed black and lit). I restarted the phone and it's running. I'm gonna give it another try.

When I create custom IPSW in redsn0w, is Cydia included?

EDIT: It's up and running. Installed Cydia using redsn0w jailbreak and then installed ultrasn0w on the phone. Works great!

[cyb3rduck]

Fab your welcome glad I could help you out As a precaution now would be an excellent time to record and save those SHSH blobs just in case!

Save your SHSH blobs for iOS 5.1.1

[PedroCheco]

Will do cyb3rduck, thanks!