Unfortunately, I'm in the same boat as you. I've had a 550g (although she now weighs less) girl whom I've had since 2/14. Never seen her eat :/ I've left rats with her overnight, done everything else. Given her a live mouse that scared her to death. Tried a live rat today that didn't scare her so much, but still nothing. I'm currently looking for asfs in my area to try next. She's losing weight now, so I'm getting nervous.

Definitely try the rat again and just drop it in and give her some space. Don't leave her unattended with the rat cause you don't want anything to happen to her. I usually cover the tub with a towel and watch through a corner so she feels more secure. I wouldn't leave it in there more than 15 or so minutes. If that doesn't work, I'd suggest asfs - they seem to do the trick for most. Good luck! I know, it sucks