Error 1011 This is caused by recovery mode being in userland (1.1.1 firmware). Error 1013 - i Phone 4 This means that the baseband did not get updated.
Removed BBFW file in the firmware folder of an unzipped IPSW. The device is bootable, if you set the auto-boot to true or use Tiny Umbrella and use "Kick Device out of Recovery".
Error 1015 This error is common when downgrading i Phones and 3G i Pads.
The problem occurs when the device's baseband has a higher version number than the baseband in the firmware you restored to.
Error 1611 i Tunes tried to enter the Restore Mode, but the device turned back to the Recovery Mode.
This can happen when updating an i Pad 2 jailbroken with Saffron gets updated to i OS 5.