Big red robot, either its head or chest is shaped like a star.  Saw it on Toonami once a while back, from what I remember it was at some kind of robot show, then there was an attack and some random kid got stuck piloting it.  Yeah, standard plot, I know, but the robots design might ring a bell.  Its been poking at the back of mah mind fer a bit now, and even if I never watch it, knowing the title might make it go 'way.