[Kalabalak]

Hello guys, I am facing really strange problem and hopefully someone can help. We have a Toyota Sienna 2008, which is fleet vehicle (without immobilizer), but the customer removed the ECU and installed into a vehicle with immobilizer for some testing purposes. After they reinstalled the module back to the original vehicle, no engine start is possible and fault code is present: B2799 engine immobilizer  system. It looks like the ECU took the security data from the other vehicle. At this point, the only solution that comes to my mind is buying another ECU that is specifically off of a fleet vehicle so that the vehicle can run without an immobilizer.

I am open to any ideas or solutions, thanks in advance!