A Saturday morning children’s show gets its third big-screen treatment with “Saban’s Power Rangers” (Lionsgate).

Regrettably, unlike the two previous films in the franchise, this latest incarnation of the popular 1990s program (then called “Mighty Morphin Power Rangers”) is more suitable for late night TV, because of a preponderance of crass humor, off-color language and inappropriate sexual references.

Such vulgar updating of a relatively wholesome (if somewhat cheesy) concept is baffling, unless director Dean Israelite (“Project Almanac”) and no fewer than five screenwriters were charged with a command to be “relevant.” That would also explain, in part, why one of the five teen superheroes, Trini (Becky G.), aka the Yellow Ranger, is now gay.

(The subject of Trini’s homosexuality is confined to a single acknowledgement that she prefers girls over boys; she does not act out her inclination).

The bare-bones of the original series, a Japanese invention adapted for American audiences by Saban Entertainment, remain. Five high school students meet in after-school detention, each there for a different reason.

Jason (Dacre Montgomery) is the football star who fell from grace, wrecking several automobiles in the process. He has eyes for comely rebel Kimberly (Naomi Scott), recently cast out of her popular clique at school. Resident nerd Billy (RJ Cyler) is brilliant but often bullied. Zack (Ludi Lin) is a cool dude cast from the James Dean mold. And Trini is a moody loner who throws a mean left hook.

The quintet meets outside class by chance at an abandoned gold mine. There they discover five shiny coins, each a different color. This is no spare change, as the trinkets emit otherworldly powers which begin to transform our teens, a la “Spider-Man,” into superheroes.

Digging deeper into the mine, they discover an alien spacecraft — and with it, their destiny. The disembodied deity Zordon (voice of Bryan Cranston) and his robot sidekick, Alpha 5 (voice of Bill Hader), have been waiting eons for our teens to take up the mantle of defenders of good over evil, in other words, become the Power Rangers.

And so, our ragtag bunch undergoes extensive Ninja-like training to learn how to “morph” into their armor-clad alter egos, each a distinctive color: red (Jason), pink (Kimberly), blue (Billy), yellow (Trini) and black (Zack).

Their reinvention comes not a moment too soon. Zordon’s ancient nemesis, Rita Repulsa (Elizabeth Banks), has been revived and is hell-bent on world domination. She has a particular penchant for gold, rampaging countless mall jewelry stores to build a colossal monster that will locate the all-powerful “zeo-crystal.”

If this sounds silly and mindless, it is, and had the film taken a different tack it would have been escapist fun for all ages.

In the end, not even the amusing gag of locating of the zeo-crystal beneath the local branch of Krispy Kreme Doughnuts — also an extreme example of product placement — can make up for the film’s excess of bad taste.

The film contains much crude humor, rough language, sexual innuendo and references to homosexuality and masturbation. The Catholic News Service classification is L — limited adult audience, films whose problematic content many adults would find troubling. The Motion Picture Association of America rating is PG-13 — parents strongly cautioned. Some material may be inappropriate for children under 13.