I tried the font exploit using the hdd swap method and now everytime I try to start the xbox it gives me error 21. I can not hdd swap the drive to repair the problem because the xbox does not unlock the hdd any more, it only gets to the error and not to the dash. I can not boot from a game either

I am using a version 1.5 xbox with a focus video encoder will the xbit I bought work with my xbox? I know there is additional soldering I must do to make it work but what about the video encoder, is there a bios that can be used with the focus? My xbit will arrive tomarrow or the next day, I got overnight delivery on it. When it arrives assuming there is a bios that is compatible with the focus chip (I heard cromwell was not) will plugging the modchip in and soldering the two additional wires allow it to boot so that I can hdd swap the drive and repair the problem? Thanks in advance