You blew it, punk: You didn't watch when CBS launched RHD this fall, so you missed Michael Mann's corrosive, cobalt blue night view of L.A. homicide cops swarming crime scenes, led by Tom Sizemore (below) in a proud, chesty performance. CBS yanked the show, but now you got a second chance, yo-yo: USA is showing the last three, unaired episodes on Monday nights starting April 7. Don't miss 'em: They begin with ''Hellbound Train,'' directed by Mann's daughter Ami Canaan Mann, featuring Sizemore going one-on-one with a subway vigilante. The series concludes with a (in the words of a Band song) shoot-out in Chinatown. TV doesn't get any more beautifully bruised than this. Join in RHD's passing or be a chump for eternity.