I have a 2000 Accord Coupe that had an F23A1 engine swap, but the F23A4 ECU was not. I am getting all sorts of error messages. I got an ECU from an F23A1, but when I put it in the car won't start the green key is flashing. I was told it would be the immobilizer, can I flash the immobilizer or ECU or should I replace the immobilizer. The local dealer says 200 to do the work the local locksmith says maybe 50 if it works, but has not in the past for him. What do I do?