Why didn't you first use iDump to backup your original FW? And then iFlash to get it updated? That way you should have your orig.bin on the USB boot stick.
iPrep would not have continued or started to flash if you did not have a valid orig.bin in the backup folder...(then you said you lost it later...bad news for you lol)...what you read about patching around the key was the Hitachi firmware. The firmware for the Hitachi's patches around the location of the key