Is your phone rooted? If it is then you cant do over the air updates, you will need to install a custom rom with ics made for it. If it is not rooted then that means the download was corrupted, you need to redownload it by deleting the update off your phone normally that is done by changing the settings to never notify about updates, then reboot the phone and re check for updates. Hope this helps..
If you have changed your bootloader's settings then you may not be able to run the OTA setup, you should restore all settings/software to stock settings/load then retry the OTA.