Some users who tried to upgrade their iPhone, iPad or iPod Touch to a newer firmware encountered during the process several errors such as error 1600, 1601, 1602 and 1604. These annoying errors may have various meanings. For example, they can tell you that your device is not eligible for upgrading or that you cannot restore it. Fortunately, developers found a way in which users can fix these problems and they can continue with the process of upgrading or restoring without any other complication. One solution in this case is related to the iREB program, which is eligible to fix this kind of problems. Before starting the guidance towards the solution of these errors, I want to mention the fact that they appear in the case of restoring and upgrading iPhone 4S/4/3GS, iPad 3/2/1 and iPod Touch on iOS 5 or iOS 6.
However, some users suggested that they solved the problem quite simply by checking the USB and replacing it. In some cases, the upgrade of iTunes represented the solution. When the USB is not the original one, sometimes there might be problems. As I told you, Error 1600, 1601, 1602 and 1604 can be solved in some cases if you take the advices above. Where they are not successful, you need to try out the second method.
The second method represents the use of iTunes to restore.
1. Connect your device to your computer and put it in the Recovery Mode.
2. Connect the USB cable.
3. Turn off your device and put it in the DFU mode.
4. When iTunes recognizes your device, you should click on OK button and begin the restoring process.
This should solve your problem. However, if this method still does not work, you have a last one to try out. This solution suggests users to install iREB on their devices but it concerns only older firmware devices such as iPhone 3G/2G, iPod Touch 2G/1G.
1. Download and install iREB and then, start iTunes.
2. Put your device in the DFU mode.
3. Close iTunes and launch iREB.
4. Once you select your device in the list open iTunes again and press the Shift Button while you click on the Restore button. Select the custom firmware and restore it.
One of these three solutions should definitely work to fix iTunes errors 1600, 1601, 1602 and 1604 on your iDevice.