'04 tl obd2 port not communicating
 

Hi, been a minute. I had my 04 tl blow a gasket (for the 3rd time) and decided to leave it for a while (a while being bout a year). One day I got the motor replaced. But since I did that, I haven't been able to start the car. The green key light kept flashing on the dashboard I was advised to change the brain box... So I got a new brain box{ecu}. Same thing... I figured I needed it programmed.. So I had a tech guy come but he says that the system can't communicate with the ob2 port... Now I'm confused and lost... Please help!! 😭 😭 😭

Does it have a properly charged battery?