tvktk

HI guys recently bought a 2011 insignia 2.0cdti Car was running when i bought it. Started it the next morning and put it in my shed. Serviced the car and done gearbox oil. When i went to start battery obviously wasn't great and car failed to start message poped up on dash Service Theft Deterrent System Have had the car at the dealer they say no response from bcm. Put a used ecu kit in from a local breakers and same issue even got security code for replacement ecu and opcom but no joy