So, you have been successful in making a custom iOS 5 for your iPhone but, when you try to put it into your device, iTunes returns an error 16xx(1600, 1601, 1603, and 1604). This is a common issue and there is a simple solution available for it. One of the above-mentioned errors basically comes up due to the fact that your device can actually determine if you are using a stock IPSW or a custom one. When you try to restore with a custom firmware, the device basically tells iTunes not to restore to that particular firmware. This is where iREB comes into play. iREB is a tool for Windows that can put your device into a pwned state so that you can install custom firmware to it. Today we will be providing you with a simple and brief tutorial on how to put your iPhone, iPad, or iPod Touch into Pwned DFU Mode with the use of iREB RC4 for Windows so that you can restore to a custom iOS 5 IPSW without facing the iTunes 16xx (1600, 1601, 1603 & 1604) error. Please note that this is a guide for Windows, Mac users will have to use Redsn0w as an alternative to iREB). Here are the steps on how to put your device into Pwned DFU mode using the iREB tool for Windows:
Firstly you need to download iREB RC4. The files will be zipped so, extract them where you want.
Now connect your device to your computer system and launch iREB-r4.exe from the files you have extracted in Step 1.
Select your device. Now you will need to put your device in DFU mode (Complete tutorial on how to enter DFU Mode) in order to proceed, just follow the on-screen instructions in iREB.
Make sure that your device is properly connected to your computer via USB cable and also do not run iTunes in the background.
Now turn off your device by holding down the Power button.
Now hold down the Power + Home button together for about 10 seconds.
After that, release the Power button while still keeping down the Home button pressed. If done correctly, your device should enter DFU Mode and iREB should be able to detect that.
As soon as iREB detects your device in DFU Mode, the L1merain exploit should now be patched into its iBoot. The patching process usually takes about 10 seconds or so.
Once done, you will get a confirmation window that informs you that your device is now in Pwned DFU state. It’s now time to launch iTunes and restore from there (make sure you have the latest iTunes).
Now you can select the iOS 5 IPSW, you will need to press the SHIFT + Restore button.
We tried our best to explain the tutorial to you in the simplest way, but if you are still having problems please comment below.