Temporarily disable your antivirus program if you are running one and try restoring in DFU mode in iTunes again. Reboot and try it again if you don't have an antivirus program installed. Try a new/different USB cable if you have one. Post the exact error code if it fails again and the point in the restore where it fails (extracting firmware, verifying with Apple, etc.) Are you using Windows or a Mac? Do you have access to another computer?