iPhone 3GS Error 28, 1600 or Stuck in DFU Mode (Black Screen) when Restoring Custom iOS 4.2.1 Baseband 6.15.00

(Last Updated On: July 1, 2020)

This is the only fix you need for your iPhone 3GS which has error 28, 1600 or stuck in DFU Mode (black screen) when restoring using custom iOS 4.2.1 IPSW with baseband 6.15.00.

You have tried everything and checked every single forum but unable to fix this issue. Essentially the NAND chip or the “hard disk” that handles the boot up process of your iPhone is corrupted. If you attempt to restore your iPhone 3GS but kept getting iTunes error 28, then it’s time to take apart your iPhone. This solution is fully tested and 99% of the time would work if you follow these instructions carefully; unless if the NAND chip is damaged.

What you need:

  1. iPhone take apart tools (precision screw driver, suction cup etc)
  2. Windows operating system (Sorry Mac users!)
  3. iTunes 10.1.2 or later
  4. iREB RC3
  5. iPhone 3GS Custom iOS 4.2.1 Firmware (you can also build it yourself with Sn0wbreeze 2.2.1)
  6. GreenPois0n RC6.1

Warning: Before you proceed, please be warned that dismantling your iPhone will void the warranty and may permanently damage your iPhone. We will not be responsible for any damage caused to your iPhone. You have been warned.


  1. Take apart your iPhone. See YouTube videos here.
  2. Remove the logic board and put it to the side for at least 30 minutes (go have coffee or play your hacked PS3). Separating the logic board from the battery clears the memory that handles the boot process. Note: You can also leave your device uncharged for at least 5 days and will give you similar result.
  3. Now re-assemble your iPhone.
  4. iREB RC3 (right click, Run as Administrator on Windows 7). Go to Recovery Mode Loop Fixer tab and click Set-Auto Boot True.
  5. Go to iREB tab and select 3GS. Your iPhone will be set to pawn DFU mode so that it can accept iPhone 3GS custom iOS 4.2.1 firmware that you just downloaded.
  6. Launch iTunes and press Shift+Restore, then point to the custom IPSW. Restore will begin and wait patiently until it’s finished.
  7. Launch GreenPois0n RC6.1 to untether jailbreak your iPhone (this takes off the hassle of rebooting via Redsn0w after installing ultrasn0w).
  8. Now you can proceed with unlocking your iPhone with ultrasn0w 1.2.

Good luck and leave your comments below if it works for you or not! If it does, consider buying us a drink by donating below! Any amount big or small is greatly appreciated. Your donation will help maintain this website.


Final note: If you intend to post this on a forum, please kindly provide a link back to this website. Thank you!



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