brake issue question from a novice

i know how to ride a bike.. that's as far as my knowledge goes, so excuse the fact that i for sure don't know the right terminology.

i got my son a bmx bike for christmas, during assembly we had to connect the front brake. with how the tension was too high to where i wasn't able to pull the wire thingy out enough. the person (who i will neither confirm or deny was a man who thinks he can fix anything) loosened the top left bolt and gave slack to the wire until it reached.

BUT NOW, the brake won't spring back?? like when you pull the handle back, it just stays like that.

help???