No crank no start after replacing battery

Car was working fine until they changed the battery and now engine wont crank and says "immobilizer is not engaged", gives a code on the security light had it checked and "says antenna not receiving signal" took out the car computer, instrument cluster, key antenna and took it to a programmer they said " all was fine and communication between those was okay" so I reinstalled it and still car wont crank, car key works as it opens locks trunk etc. I have already disconnected the battery overnight and cables one to another in order to drain energy from the system with no luck.
i there a way I can by pass the immobilizer or reset it?
would very much appreciate any help.