An early scene in the film has Marty McFly and his band The Pinheads auditioning for the high school dance. Lewis has an uncredited cameo in this scene, where he plays a teacher who is judging the auditions. The group plays the beginning of “The Power of Love,” but before Marty can sing a note, Lewis cuts them off, telling them, “I’m afraid you’re just too darn loud.”

The Power of Love
Huey Lewis and the News 

Source: ♫ The Power of Love ♫ (Redux) | Filosofa’s Word