You messed up very well
But it's possible to repair.
As you say you can use config magic to restore your eeprom
from file or just edit it on the fly.
I hope you can see something on the screen.
Could be that the xbox is set to PAL/NTSC.
Therefore you can download a switch disk
which will let you blindly switch from PAL/NTSC.
If all that doesn't work you will have to flash
your eeprom manually... (don't ask me how)