The misspelling of genesis in the latest “Terminator” title should clue audiences in as to how dumb it is.

The film relentlessly assaults the senses with bullets and explosions to distract viewers from its incomprehensible plot, and it ultimately raises dozens of time travel-related questions that its writers aren’t creative enough to answer. After the disappointing “Terminator 3: Rise of the Machines” and the underwhelming “Terminator Salvation,” “Terminator Genisys” does little to save the ailing franchise.

The movie begins in 2029, at the end of the war between humanity and Skynet, a supercomputer that controls legions of robot soldiers. The leader of humanity, John Connor (Jason Clarke), defeats Skynet but not before the artificial intelligence can send a terminator back to 1984 to kill his mother, Sarah (Emilia Clarke), and prevent his birth. Connor sends his best soldier, Kyle Reese (Jai Courtney), back in time to save her. Sound familiar?

The plot diverges from the first film’s when Kyle arrives, effectively making “Genisys” a reboot and erasing James Cameron’s originals. Reese discovers Sarah already has another protector, a terminator called “Pops” (Arnold Schwarzenegger), and knows she will give birth to John.

Before long, Sarah and Kyle travel into an altered 2017 using Pops’ homebrewed time machine and attempt to stop Judgment Day. But John, whom Skynet has transformed into a deadly new terminator, arrives to battle them.

Jai Courtney and Emilia Clarke deliver underwhelming turns as their respective iconic characters. Hollywood has tried making Courtney a leading man for a while now, but he lacks the charisma needed to carry a picture of this magnitude. Clarke is miscast, unconvincing as the tough rendition of Sarah Connor. Unlike Linda Hamilton, who played Sarah in the first two “Terminator” movies, Clarke never looks or acts like a credible action heroine.

The film forces a romance between Kyle and Sarah simply because it happened in the first one. It doesn’t arise because of the characters’ growth or their compatibility — Courtney’s and Clarke’s versions have zero chemistry. When the pair finally kiss, viewers will be scratching their heads and wondering what those two saw in each other in the first place.

On the other hand, Schwarzenegger is the best part of “Genisys,” injecting humor and heart into an otherwise bland, by-the-books picture. Some of Pops’ best moments are his dorkiest — he repeatedly asks Sarah when she is ready to “mate” with Kyle, much to her chagrin, and smiles awkwardly when the police take his mugshot.

But Schwarzenegger’s performance alone can’t save “Terminator Genisys.” Director Alan Taylor and screenwriters Patrick Lussier and Laeta Kalogridis provide no context or explanation for the film’s series of increasingly ridiculous events, making it hard to care about what’s happening onscreen. Instead of sympathizing with the characters and going on their journey with them, viewers will spend most of their time struggling to understand all the alternate timeline nonsense.

The film also wastes the potential of using John Connor as the villain. The twist itself is surprisingly fresh and, by making John a bridge between man and machine, the writers could’ve mined it for some serious thematic heft. “Genisys” squanders this opportunity by turning John into another generic villain the heroes have to blow to smithereens. It’s hard to say what’s more tragic — that the hero of the “Terminator” franchise has fallen, or that no one else in the film really cares.

As a sequel, “Terminator Genisys” adds little to the story, and, as a reboot, it sets up the series for a bleak future. If future “Terminator” films will offer the same level of quality as “Genisys,” it’ll probably be best to terminate this franchise for good.

Title: “Terminator Genisys”

Running Time: 126 minutes

MPAA Rating: PG-13

Score: 4/10