The cigarette lighter on a 2012 Scion xb is out. Googling I see two fuses are needed... the #7 fuse and the #21 ACC . I can't get the fuse box cover off. What is the secret? How will I know which fuse to replace. O'Reilly's tells me they only carry one fuse for the cigarette lighter. It costs $50, and is not labeled as to which fuse. What to do?