500 grams is probably large enough for small rats, to be honest. She is probably holding out for a larger meal!

If temps and humidity are perfect like you say, just keep waiting. Sometimes they go through a fasting period as juveniles (I have a yearling cinnamon at home currently doing this in fact) where for no apparent reason, they stop feeding for a period of time.

If she's not losing weight, and is otherwise acting normally, I'd keep offering at least jumbo sized mice (if not small, weanling rats) once a week until she does start eating.

-Jen