Hello there, JulieFromBootle.
This article references your error message and provides helpful steps on resolving your issue:
iTunes: Specific update-and-restore error messages and advanced troubleshooting
http://support.apple.com/kb/TS3694#error1601
Error 1601 is listed further below but recommends the steps for resolving Error 1604:
This error is often related to USB timing. Try changing USB ports, using a different dock connector to USB cable, and other available USB troubleshooting steps (troubleshooting USB connections. If you are using a dock, bypass it and connect directly to the white Apple USB dock connector cable. If the issue persists on a known-good computer, the device may need service.
If the issue is not resolved by USB isolation troubleshooting, and another computer is not available, try these steps to resolve the issue:
- Connect the device to iTunes, confirm that the device is in Recovery Mode. If it's not in Recovery Mode,put it into Recovery Mode.
- Restore and wait for the error.
- When prompted, click OK.
- Close and reopen iTunes while the device remains connected.
- The device should now be recognized in Recovery Mode again.
- Try to restore again.
If the steps above do not resolve the issue, try restoring using a known-good USB cable, computer, and network connection.
Follow the steps listed above for Error 1604. This error may also be resolved by disabling, deactivating, or uninstalling third-party security, antivirus, and firewall software. See steps in this article for details on troubleshooting security software.
Thanks for reaching out to Apple Support Communities.
Cheers,
Pedro D.
