From the [http://support.apple.com/kb/ts1275|Apple support site] it appears that "Error 23, 28, 29, 1011, 1012, 1611: These errors may indicate a hardware issue with your device. Follow the steps in this article and also attempt to restore while connected to a known-good computer and network to isolate this issue to the device. If the IMEI or MAC address is missing or is a default value, this can also confirm a hardware issue."
From the [http://support.apple.com/kb/ts1275|Apple support site] it appears that "Error 23, 28, 29, 1011, 1012, 1611: These errors may indicate a hardware issue with your device. Follow the steps in this article and also attempt to restore while connected to a known-good computer and network to isolate this issue to the device. If the IMEI or MAC address is missing or is a default value, this can also confirm a hardware issue."