What is the number in the name of the XDF file you are using to edit your OS? I'm not familiar with 12209203 and I don't believe there is an XDF for it but the two MUST be the same. If you edit the 12209203 OS with some other random XDF not made for 12209203 then yea, you just created yourself a checksum error.

I hope you still have a pristine undamaged copy of the OS somewhere safe. Or better yet, you are prepared to modify a different, more widely understood known OS BIN that does have a matched XDF file for the proper internal OS definitions.

Rick