stop me from doing something bad to my 3gs

[drice]

I have the following iPhone 3GS:
Firmware: 3.1
Baseband: 05.11.07-6.4_M3S2
Bootloader: 6.4
Bootrom: iBoot-359.3 (old bootrom)

The phone has never been jailbroken. I hope to jailbreak the phone with PwnageTool then unlock with ultrasn0w for use with T-Mobile. Does that sound like a reasonable plan?

Can I use PwnageTool 4.1.2 to jailbreak my iPhone to firmware 4.1, or does it require I jailbreak my 3.1 firmware first?

Should I use PwnageTool to create a custom 3.1 ISPW or should I create a custom 4.1 ISPW?

[i.Annie]

If you have a Mac, using PwnageTool will work to get to 4.2.1. You don't need to jb it where it is now, just as long as you use PwnageTool to set it into pwned DFU after creating the custom fw. Then you can option+restore to the custom 4.2.1 fw just fine.

[Mes]

Download Tiny Umbrella, connect the phone, select save all. SHSH blobs are required for all but the current version (4.2.1).

The Firmware Umbrella - TinyUmbrella

And as iAnne stated, a custom firmware (made with Pwnage) is required to preserve the unlock.

[drice]

If you have a Mac, using PwnageTool will work to get to 4.2.1. You don't need to jb it where it is now, just as long as you use PwnageTool to set it into pwned DFU after creating the custom fw. Then you can option+restore to the custom 4.2.1 fw just fine.

I downloaded the iPhone 3GS 4.2.1 firmware here:
ModMyi Forums - Downloads - iPhone 3GS 4.2.1

But PwnageTool will not open that file and gives me the following error:
Wrong firmware bundle selected


Should I be using the 4.1 firmware bundle?

[i.Annie]

Is it in .ipsw format and not .zip?

[drice]

The file name is iPhone2,1_4.2.1_8C148a_Restore.ipsw.

I downloaded the 4.1 firmware version (iPhone2,1_4.1_8B117_Restore.ipsw) and PwnageTool is happy with that.

I am not sure what is going on, but I am going ahead with the 4.1 update.

OK, using the 4.1 firmware does not work either. PwnageTool is able to make the custom ispw, but during the restore, iTuens says, "The iPhone could not be restored. The device isn't eligible for the requested build.

[Simon]

To make a custom 4.2.1 for a 3GS you first need to add the 3GS bundle to pwnage tool as described in update #3 on the dev team blog.

[i.Annie]

You would also need SHSHs to do 4.1 if you choose to go that route.

[drice]

The following related thread might be useful for anyone else who is also trying to unlock a similar phone with Pwnagetool:
Pwnagetool does not recognize 4.2.1 firmware bundle