....then you have to edit EEPROM
For what? How do you think the immobilizer code in the eeprom affects the program inside of flash chip? I flashed TT file for A6, and M-box file for A6 and allroad, other A6 chip for allroad and immo OK. Key code reads by instrument cluster(or immo box for a4) and ecu just compare immo code with key code from i-cluster and decides to run or not.
But I'm not sure that 250file(2001) will run at 230(2000), but for other reasons, not because of IMMO. First compare MLOFS -make sure that the MAF the same. Then read your stock chip and try flash 250file in boot mode. And run a car. If not running then flash back stok. And be sure that new file supports the automatic box ECU coding. it`s all