Any tips for a baby that used to do fine and now hates the bath?
Bring in some new toys or favorite toys that can get wet. The idea is to distract him long enough for him to remember that bath time is fun or at a minimum tolerable.
You could try going to a swimming pool to become more comfortable with water again. A parent child swim class is good because it teaches songs and other little things you could do in the bath to form a routine.
My daughter also went through a similar phase; she would scream bloody murder throughout the whole bath. Then, she was fine after a few weeks. During this time, water over her head and face was the worst. See if that is the case n try to get through it fast.
My daughter did the same thing. She loves water, except for a couple of weeks when she was a year old. It was like torture. Grew out of it quickly.