except he's already in a lease agreement. Prior to signing, yeah all bets are off.
Once you have signed, he could care less if you move out...doesn't change the terms of the lease.
Also bank errors in payment are not lease breakers.
To me this sounds just like when my car payment went to my insurance company and they cashed and deposited it. My car creditor only got the insurance payment which they also deposited.
I had to pay additional to the car company. The insurance company would not issue a refund.
Didn't matter that the payee on the check was wrong...it was totally legal.
Sounds like this situation, only the landlord didn't get anything and doesn't know where the money went.
Everyone is on the landlord because the place looks so crappy, however; this is how the OP accepted the place. No one is guaranteed a spit polished palace in a lease which is why you look at a place and don't sign anything until it is to your liking.