Connecticut Rental law

My brother is going through a tough time with his first landlord. She randomly started fliping out on him, over his "loud" car that he had when he moved in. (Which she never had a reasonable discussion about) They became very mad at each other, and my brother wanted to move out, which she agreed to. But now she thinks its HIM that broke the lease by asking for a mutual agreement to leave, and she says she will keep the $1050 security deposit. She refused to sigh anything, and now says she will tow his car if he parks in his designated spot. So she is forcing him out of his apartment and keeping the security deposit at the same time.

The only valid reason he sees that she might claim part of his deposit is small marks his futon left against the wall. Otherwise the apartment is in the same condition as when he came. Unfortunately he did not take pictures or anything when he first moved in though, so he is afraid she will claim damages that aren't his. Any advice on what to do from here.