iPhone 3GS Recovery Loop and Error 1015 Fix with Custom Firmware 4.2.1

For iPhone 3GS users who have upgraded to baseband 6.15.00 but are stuck in a recovery loop, this instruction will help you resolve this issue.

If you have iPad's baseband 6.15.00 installed into your iPhone, iTunes will not allow you to restore with the original firmware as it does not recognize this baseband on an iPhone.

1. Download custom firmware 4.2.1 for iPhone 3GS [396.46MB download link]
2. Use Redsn0w 0.9.6b8 and select pawn DFU mode only option [Windows or Mac]
3. On iTunes, do a shift restore and point to the custom IPSW file you have just downloaded
4. If you encounter error 16xx, use iREB-4.0.x-4.1-RC2 to fix this issue [download link, Windows version only]
5. Repeat step 3 by doing a shift restore
6. After restore is completed, your iPhone will reboot automatically and you will get to the emergency screen
7. Use redsn0w again and chose the option just boot tethered right now
8. Your iPhone will reboot showing a Pinapple logo and your iPhone it will be activated automatically