"Marilyn: The Untold Story" should have stayed that way.The three-hour ABC film, tomorrow at 8 on Channel 7, is not really a movie but a mere collection of scenes, vignettes that alternately announce that Marilyn Monroe was enigmatic, difficult, capricious, troubled and of course, unhappy as only rich and famous sex symbols can be.

Producer Lawrence Schiller was a young photographer on the set of "Something's Got to Give," the film that went unfinished because Monroe died during shooting in 1962. Schiller's film tribute to her uses Norman Mailer's "Marilyn" book "as the basis for the film," ABC says, but authenticity doesn't really matter in such exploitation; this grime is a betrayal no matter how you look at it.

Millions probably will look at it, and the picture is watchable enough in that point-A-to-point-B TV movie way. Most TV movies are to film what the Rolodex is to literature, this one included. The story unfolds tritely and without dramatic shape, opening as anyone could predict (just like ABC's similarly flavorless "Elvis") with Monroe near her death, in decline, then flashing back to a tortured childhood for the long chronological trek forward.

Catherine Hicks is inadequate in the role of Marilyn Monroe, as anyone but Marilyn Monroe would be, but occasionally in long shots she does evoke that bubbling, lighthearted, friendly sexuality that usually eavdes Monroe impersonators. Most of the time, though, she is more reminiscent of (though not nearly so pungent as) Dorothy Comingore's Susan Alexander Kane. Some of the incidents meant to be sweetly evocative do come off, but the level of character analysis is pretty much the old Hollywood slush about Hollywood.

Married to a soldier during the '40s, the young woman born Norma Jean Baker takes pity on a wet cow on their wedding night and drags the thing indoors. Posing for an innocent photo on the old wartime assembly line, she is flattered when a photographer tells her, "The camera loves you" (ah yes, the "love me, love me" syndrome) and later says ingenuously, "I want to be a movie star; what's wrong with that?"

Some of the remarks sound much too farfetched to have ever gotten remarked. "Someday I'm going to find somebody who respects me," Marilyn resolves. And husband Arthur Miller, the playwright, is made to say, "You face more demons every day than most people face in a lifetime." The portrait is not complete or original enough to make the flare-ups of temperament and insecurity seem anything more substantial than spankable childishness.

If Hicks does a fairly creditable job under the circumstances, most of the other impersonations are patently ridiculous -- Frank Converse as a stiff and sullen Joe DiMaggio, playwright Jason Miller as playwright Arthur Miller, Viveca Lindfors as a bedraggled dramatic coach who wants Monroe to play the classics or something and scolds her with such lacerations as, "Your mind is on Joe DiMaggio!" Even more hootable are actors in small roles playing such Monroe costars as Laurence Olivier, Clark Gable and Montgomery Clift.

The tinkly "sensitive" piano music on the soundtrack and the dum-dum bullets of pop psychiatry become extremely tiresome, and perhaps Hicks deserves credit for sustaining interest in the Monroe-like character while surrounded by such hoary banality. To end on a thoughtlessly vulgar note, closing credits are pasted across the freeze-frame of Hicks as the dead Marilyn. Hey, those Hollywood boys are all class, aren't they?