In my personal opinion...assist feeding is only for hatchlings who are difficult to get started on their first few meals. If your snake is 475g...that snake has eaten before and given time...will eat again. I had a female go back on feed 2 weeks ago who prior to that had been fasting since October 7, 2010. Now she is eating like she...well...like she hasn't eaten in 9 months. She has had another fast lasting 6+ months prior to that. When she eats, she's a monster...when she doesn't...forget about it.
Give it time, reduce the frequency of feeding attempts, reduce the size of the prey offered, and wait it out. Your snake will eat again when it is ready. One indicator to watch for...almost all of my long term fasters have gone back on feed immediately following a shed.