Still will not crank horn keep blowing

What is your question?

As subjected took battery to be tested need battery brought it home put it into the car the horn will not stop blowing and it will not turn over or crank. Someone said it may be in theft mode. We have tried using the control to stop the horn also tried use the key to lock and unlock the door but nothing works other than unpluging the battery to stop the horn. How can I get it out of theft mode?