OK, so redsn0w was released yesterday that will downgrade iPad baseband 6.15.00 to 5.13.04 but it didn’t work for some. Here’s a fix which you can try.
UPDATE #2: Did you know? AT&T iPhone can now be officially unlocked. Click here.
UPDATE #1: Try the latest version of Redsn0w 0.9.14b2 which supports more variations of NOR chips used in iPhone 3G or 3GS.
I tried to downgrade it while the iPhone 3GS was running on iOS 5.1.1. When the process was completed, the phone booted up but it was still showing iPad baseband 6.15.00. I found a simple solution which hopefully would work for you as well.
UPDATE #1: This doesn’t work for many people based on the comments I received. Let’s see if there’s a pattern to this problem. If you manage to downgrade yours successfully, share your comments. I’ve read some comments that clearing the cache on redsn0w would help fix this problem.
UPDATE #2: Added method 2 below. Thanks to Rimai B on iPhoneGPSFix Facebook group.
Firstly, use this iPad baseband downgrade guide I posted yesterday. Once done, if you still have baseband 6.15.00, try the following:
1. Build custom iOS 4.1 either with redsn0w or sn0wbreeze. You can also download custom iOS 4.1 for 3GS or you can use any custom iOS 4.x for iPhone 3G since it doesn’t require SHSH signing.
2. Put iPhone into pawn DFU either with iREB or redsn0w.
3. Launch iTunes and press Shift+Restore (Windows) or Option+Restore (Mac). Since Apple is still signing iOS 4.1 for iPhone 3GS, make sure your hosts file doesn’t point to Cydia server (though it’s OK if you have SHHS for iOS 4.1 saved there).
4. Wait until the restore is complete.
5. When your iPhone reboots, you should see your baseband is now downgraded to 5.13.04.
Pretty strange but this would work for sure.
1. Use iTunes to restore stock Apple iOS 5.1.1 (9B206) IPSW.
2. Run Redsn0w 0.9.14b1.
3. Select Clear Cache from “Extra’s > Even More” page.
4. Select IPSW from “Extras” page and select the location of your iOS 5.1.1 (9B206) IPSW.
5. Power Down the iPhone (slide to power off).
6. Click Jailbreak and tick only the “Install Cydia” option.
7. Enter DFU mode and allow Redsn0w 0.9.14b1 to Jailbreak your iPhone and install Cydia.
8, Re-Run Redsn0w 0.9.14b1.
9. Select Clear Cache from “Extra’s > Even More” page.
10. Select IPSW from “Extras” page and select the location of your iOS 5.1.1 (9B206) IPSW.
11. Power Down the iPhone (slide to power off).
12. Click Jailbreak and tick only the “Install iPad baseband” option.
13. Enter DFU mode and allow Redsn0w 0.9.14b1 to install the iPad baseband.
14. When the iPhone reboots, either restore from iTunes backup or create a new phone to get access to Home screen and Apps.
15. Run Cydia, wait for it to update and then install Ultrasn0w.
16. Make sure the iPhone is activated and working with iPad baseband, e.g. make a test call.
17. Re-Run Redsn0w 0.9.14b1.
18. Select Clear Cache from “Extra’s > Even More” page.
19. Select IPSW from “Extras” page and select the location of your iOS 5.1.1 (9B206) IPSW.
20. Power Down the iPhone (slide to power off).
21. Click Jailbreak and tick only the “Downgrade from iPad baseband” option.
22. Enter DFU mode and allow Redsn0w 0.9.14b1 to downgrade your iPhone baseband.
Note: If one the above methods worked for you, leave your comments below with your model number e.g. MCxxxLL and production date based on the serial number e.g. xx809 is week 9 of 2008.
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