That's terrible what they did to her.
I used to do a lot of rescue work when I was younger. I'm not an expert by any means. I did pretty much what your doing. Lots of baths, and let them eat whatever at first. Slowly try and introduce more foods. let them get their strength up before you do anything drastic. Sometimes the color of the food made a difference. I had some that would be intrigued by a new bright color, or would be willing to try a new food the same color as their favorite. And I found all my iguanas would eat better if their salads had a wide variety of colors. It's been like 10 years since I had iguanas, but I think I read that color is very important to them. Lots of different colors are exciting.