Take it back to Fraud and tell them that "we can't find anything" is not an answer. She is under warranty they need to be doing something about it. They should find the issue or be replacing stuff until they fix it. There is no way it should be up to you to find out what it is, or buy things to try and fix it. That is what warranty is for! Sorry - rant over.... I would be checking all the interior lights to firstly make sure they all work, and then see if any have been left on. If one of them doesn't work and it is shorting you will have an issue like Infamous said.... Good luck with it but!