iPhone Factory resetting jailbroken iPhone 3GS with 06.15.00 baseband

I grudgingly had to jailbreak and unlock my 3GS when I moved from the US a couple of years ago as AT&T did not unlock out of contract phones at the time. As a result I had to 'upgrade' to the 06.15.00 baseband and use ultrasn0w.

Now that redsn0w has finally made it possible to downgrade to the 05.13.04 baseband and AT&T unlocks out of contract phones I would like to factory reset my iPhone and set it up as new. I have tried looking all over the Internet to see if this is possible and though the topic has been covered in great detail I cannot find any specific information. Here are the questions that I would love to get answers to:

1 - Can I remove ultrasn0w and unjailbreak (by removing Cydia perhaps?) and if so how do I do so and when? Is this to be done before downgrading to 05.13.04 or after?

2 - Can I simply connect my phone to iTunes and restore it after I downgrade it to 05.13.04? If so then can I update it to the latest iOS version compatible with my phone?

3 - If this process is possible and successful then will my phone behave like any other non-jailbroken phone?

I am afraid of bricking my phone as I have never played around with the jailbreaking process and would appreciate help!

nerak99 said:

What iOS have you put onto it?

Click to expand...

It is currently on 4.3.3.

Here is some more information that may be of help.

Firmware - 06.15.00
iOS version - 4.3.3 (8J2)
SHSH blobs saved by Cydia - iOS 4.1, 4.2.1r1, 4.3, 4.3.5, 4.3~b1, 4.3~b2, 4.3~b3, 6.0.1
Model - MB717LL
Serial Number (First 5 digits) - 88935

I was wondering whether I could simply follow the redsn0w based downgrade process for going from 06.15.00 to 05.13.04. Would the fact that I do not have SHSH blobs for my current iOS version (4.3.3) pose problems?

I would like to completely wipe all traces of the jailbreak and unlock since I don't need either now. I also want to be able to update to iOS 6 (and install future updates). I have searched all over the Internet but cannot seem to find a definitive step by step guide to my problem. This is the first time that I am attempting the jailbreak/unjailbreak process and so will greatly appreciate a detailed response.

Here's a step by step list to unjailbreaking and restoring an iPhone 3GS on 06.15.00 to factory settings. This may come in handy for other 3GS users who were stuck on an old version of iOS and who no longer want to be jailbroken as AT&T now unlocks out of contract phones.

1 - Use this guide to downgrade your baseband from 06.15.00 to 05.13.04 using redsn0w. Make sure to use redsn0w 0.9.14b2 and not a newer version as I read somewhere online that 0.9.14b2 works best.

2 - If you are a current or former AT&T subscriber and your iPhone is eligible for an unlock then use this form to request it and proceed to the next step once you get a confirmation that your iPhone has been unlocked.

3 - Once you are on baseband 05.13.04, put your iPhone in DFU mode to do a complete restore, remove the jailbreak and set it up as new. See this video for reference on how this is done.

There are many tutorials available online which outline the baseband downgrade process but they use the older and more cumbersome process that is based on redsn0w 0.9.14b1. The process I have linked to above was much simpler and worked just as I expected it to.