If you hit a 1604, 1603, 1602, 1601, 1600 error while trying to restore your iPhone with a custom iOS 5.0.1 firmware file created using Redsn0w then there is now a way to bypass the error.iH8sn0w, developer of Sn0wbreeze has released a new version of iREB tool after almost 10 months, which is compatible with iOS 5.0.1.


iREB is a tool that will put your iOS device into a pwned state so that you can upload custom firmware to it.In addition to the iOS 5.0.1 support, iREB r5 includes a number of fixes and improvements:

• Much smaller file size (390kb).
• Fixed USB 3.0 issues.
• iREBs speed for the iPhone 2G/iPhone 3G/iPod Touch 1G has
• increased significantly!
• Fixed rare DFU detection issues.
• Updated limera1n/steaks4uce payload to not hook "cmd_go"
• on 4.x images (nothing severe, but useless here).

iREB is currently available for only Windows. You can download iREB r5 using this link.
We havent tried it out yet, but if youre looking for a step-by-step guide, you can checkout below to get an idea on how to use it.
====How To Fix 1604, 1603, 1602, 1601, 1600 Error While Restoring Custom iOS 4.2.1 IPSW Firmware File Using iREBIf you hit a 1604, 1603, 1602, 1601, 1600 error while trying to restore your iPhone with a custom iOS 4.2.1 firmware file created using Sn0wbreeze 2.2 for Windows or PwnageTool 4.2 for Mac then there is a way to bypass the error.iH8sn0w, developer of Sn0wbreeze has released a new version of iREB tool, which is compatible with iOS 4.2.1.

iREB is a tool that will put your device into a pwned state so that you can upload custom firmware to it.iREB RC3 supports the following iOS devices:

• iPhone 2G, iPhone 3G, iPhone 3G[S] (old & new bootrom), iPhone 4
• iPod Touch 2G (MB & MC), iPod Touch 3G, iPod Touch 4G
• iPad
• Apple TV 2

iREB is currently available only for Windows users.Before we start please note that that jailbreaking your iOS device may void its warranty and hence proceed with caution and at your own risk.You can follow these simple step-by-step guide to bypass the 1604, 1603, 1602, 1601, 1600 errors:

• Download the latest version of iREB from iH8sn0w
• Start iTunes (iREB needs iTunes 10 or above, it’s a good idea to use the latest version of iTunes – iTunes 10.1.2 as of now)
• Put your iOS device in DFU mode by following these steps:
  • iPhone/iPad/iPod Touch
    • Connect your iPhone/iPad/iPod Touch to your computer
    • Turn it off
    • Hold power and home together for 10 seconds (exactly).
    • Release power but keep holding home until the computers beeps as a USB device is recognized
    • A few seconds later iTunes should detect your iOS device
  • Apple TV 2
    • Connect your Apple TV 2 with your Computer via microUSB
    • Now reboot your Apple TV by holding down Menu + Down buttons together for around 6 seconds
    • After reboot, immediately hold Menu + Play until you see the message in iTunes saying that Apple TV in recovery mode is detected
• Now close iTunes and launch the iREB tool that you had downloaded earlier
• Click on the relevant device from the iREB screen and wait for few seconds until you get a white or red screen on your iOS device
  
• Now start iTunes again and select your iOS device from the left hand side side bar
• While on the iTunes window, hold the Shift key and click on the Restore button. (This is a VERY IMPORTANT STEP as just clicking the ‘Restore’ button without the ‘Shift’ button will result in restoring your iPhone with the latest firmware, by holding down the ‘Shift’ button, allows you choose the custom iOS 4.2.1 firmware file created using PwnageTool or Sn0wbreeze)
• Navigate and select the custom iOS 4.2.1 IPSW file to restore your iOS device with it

You should now be able to successfully restore your iOS device with the pre-jailbroken iOS 4.2.1 firmware file without hitting the 1604, 1603, 1602, 1601, 1600 error.