iPhone 3GS on 3.1.3 with baseband 06.15.00

[vandelayind]

So if I wanna go to 4.2.1, I have to follow option+restore with the ipsw for 4.2.1, right?

Also, will there be any chance for me to downgrade back to 3.1.3, if I don't like the untethered jailbreak?

[Simon]

Nope you can never go back to 3.1.3 without SHSH. Since you have iPad baseband you will need to restore to a custom 4.2.1 made with pwnage tool.

[vandelayind]

How do I go about updating using pwnagetool 4.1.3? Are the steps listed below correct?

Steps to Update iPhone 3GS Using PwnageTool 4.1.3:
1. Download PwnageTool 4.1.3
2. Download iPad iOS 3.2.2
3. Download iOS 4.2.1 firmware for your iPhone (3GS).
4. Launch PwnageTool and select iPhone 3GS.
5. Detect iOS 4.2.1 IPSW.
6. PwnageTool will provide you with the option to upgrade your iPhone baseband to an iPad baseband. Click Yes to continue.
7. Detect iPad iOS 3.2.2 IPSW.
8. Click YES to create iOS 4.2.1 custom IPSW for your iPhone
9. Click NO, as you are doing this for unlock purpose only.
10. Wait while PwnageTool creates iOS 4.2.1 custom IPSW which will jailbreak your iPhone on iOS 4.2.1 when restored through iTunes.
11. Once done, connect your iPhone to your Mac through USB cable and hold down the Power and Home button simultaneously for 10 seconds, after 10 seconds release the Power button but continue holding the Home button until PwnageTool detects your iPhone in DFU mode.
12. Once done, you will see iOS 4.2.1 custom IPSW file for your iPhone on your desktop.
13. Update using option+restore in itunes using custom IPSW.

[Simon]

You dont need the ipad baseband or ipsw as you already have that. Make the custom firmware with no baseband update.

[vandelayind]

When I choose the 4.2.1 ipsw file in Expert Mode, I get a message saying 'Wrong Firmware Bundle Selected'. What am I doing wrong? I am using PwnageTool 4.1.3

[Simon]

See update 3 on the dev team blog. You need to download the 4.2.1 3GS bundle and drop that in pwnage tool first.

[vandelayind]

So I updated my phone to 4.2.1, but I have 1 issue. How do I jailbreak the phone and install cydia?

[Simon]

You have to use redsnow as stated in update 3 on the dev blog. It is just a minimal 4.2.1 bundle. So just open redsnow point it to 4.2.1 regular firmware then install cydia.

[vandelayind]

So I installed cydia via redsnow. I then used ultrasnow to unlock my device. After the software ran, it prompted me to Restart Device. Since then my phone has been stuck on the apple logo. I tried to put the phone in dfu mode and restore it with the custom ipsw file, but it gave me "Error 1600". Is there a solution to this problem?

[Simon]

You get error 1600 when the phone is not put in pwned dfu mode with redsn0w or pwnage tool first before restoring to the custom firmware.

Also you probably got stuck in boot loop after because you have to run redsnow and choose boot tethered every time you reboot or power off the device. You may be able to just do that now instead of having to go through the whole restore process again.

[vandelayind]

You were right, I just ran redsnow and choose boot tethered. Now the phone is successfully unlocked. Just for a final clarification, will I have to JB and unlock the phone everytime I reboot? Also, if the battery dies, then do I have to plug in the phone ----> run redsnow boot tethered before or after the phone turns on?

[Simon]

You have to use redsnow to boot every time.

[the_saint07]

After having installed 4.2 in a 3G I tried downgrading and end up in the same dead end everyone talks about. At that point I did not saved my SSH so I couldnt upgrade again.

I trashed the phone for a few weeks and yestarday tried again, for my surprise it was a success. Here is what I did.

Already having iPad baseband I restored to 3.1.2 ips (using Shift+restore), after it finished it gave me the expected error that point out that my baseband is newer than the firmware.
After this the phone is in recovery mode. I used tiny umbrella to get it out of it (proceeded to save the SSH with tinyumbrella) and then use RedSnow 0.94 to jailbreak it.

This was also a success but the phone was not activated, by chance i found my old AT&T SIM card, so i placed it in the phone and hit activate, this allowed me to get into the iOS.

Now i just had to download the unlock software from cydia and i was done.

I cannot ensure this will work but mine is working great and with the speed of 3.1.2.