What can I do if I was paid with a bad check?

My brother did some lawn work for a lady as a side- job. She paid him with a check. My brother doesn't have a banking account, so he had to cash the check at a check-cashing business. He received the money and assumed everything was fine and normal, until the check-cashing business contacted him regarding the check. They said that it was a bad check (real, but it bounced) and that now he would be the one responsible for paying back the money. We both assumed that since she is the one who wrote the check, that it should be her responsibility to pay it back since my brother had no idea and just thought he was getting paid for a side-job. However, the bank is saying otherwise. Are they just trying to get the money any way they can, or is he really the one responsible? Please help! Thank you!