The big problem with the “Terminator” movies is regeneration. Not just the regeneration of the futuristic robots of the title: a villain, or even a hero, that just keeps picking itself up, dusting itself off, and resuming its pursuit (or protection) of humans time after time gets to be a pretty stale tic after awhile. But the larger problem is that the franchise itself keeps replicating. James Cameron’s original 1984 movie was a tight, viscerally exciting sci-fi action movie, but the sequels grew increasingly bloated and effects-laden, and by 2009 the fourth installment, “Terminator: Salvation,” one came away with the feeling that the filmmakers had gone to this well at least once too often.

This being Hollywood territory, that hasn’t stopped them from making yet a fifth trip, of course, and so we have Alan Taylor’s “Terminator: Genisys,” an attempted reboot that’s predictably efficient in terms of its visuals—and gives Arnold Schwarzenegger the opportunity to reprise what remains his signature role, in triplicate no less—but unforgivably loud, repetitive and ultimately pointless from a narrative perspective. The script by Laeta Kalogridis and Patrick Lussier earns points for trying to trying to add some new wrinkles to the series mythology, but in doing so it ties itself up in chronological knots—a common defect in time-travel stories—before ending up, in a post-credits blurb for yet another sequel, by saying “never mind.”

The movie begins in “Salvation” mode, with John Connor (now played by Jason Clarke, replacing Christian Bale) leading his rebel forces in a culminating battle against Skynet, the outfit that caused the nuclear catastrophe of 1997 that turned the world into a machine-controlled dystopia in which the few remaining humans were hunted down and killed—or turned into resistance fighters. One of John’s most committed followers is strapping young Kyle Reese (Jai Courtney), whom years earlier he’d rescued from a terminator. Their final assault on the Skynet camp succeeds, but before the final weapon—the time-travel machine—can be seized, it sends the original terminator (Schwarzenegger, in young, rather waxy CGI form) back to kill Sarah Connor (Emilia Clarke) in 1984, as prescribed in the original film. Reese volunteers to follow the T-800 to the mid-eighties to save Sarah and make sure Skynet doesn’t win a preemptive victory.

It’s at this point that the screenplay begins playing with the “established” order of things, because Reese finds not only a more advanced T-1000 (Byung-hun Lee, doing the Robert Patrick bit from “Terminator 2: Judgment Day”) on his trail, but finds that Sarah is well aware of the whole Skynet scenario and is being protected by the kinder, gentler T-800 (Schwarzenegger, of course) that first appeared in that same film but now has been around for years, first saving Connor when she was a little girl. (An explanation for how that happened is probably given somewhere, but if so it might elude you. Anyway, they’re so close she calls him “Pops.”) He—it if you prefer—and Sarah quickly demolish the original T-800, eliminating the time-line of “Terminator 1,” and then dispatch the T-1000 while saving Reese, eliminating much of “Terminator 2” (though its scenario has already been pretty much jettisoned, since Sarah’s child has not yet even been conceived, let alone born).

The plot then shifts into time-travel mode again as Sarah and Kyle zip into the future to prevent the apocalypse from occurring. But they don’t go to 1997—they choose 2017, the year that Reese recalls (in an inexplicable memory from what might be a true or false childhood) that Skynet’s takeover of the nuclear-weapons system originated with the introduction of a software system called Genisys in that year—a so-called “killer app” that promised to tie together all digital operations in one seamless bond of interconnectivity. So the new mission of Sarah and Kyle, along with the now-aged T-800, again played by Arnold, is to prevent Genisys from going on-line. But a further complication arises with the arrival of none other than John Connor himself, who’s ostensibly there to help our heroes but turns out to be a man with an agenda of his own.

It wouldn’t be fair to detail what follows—and probably impossible, since the script tosses in so many temporal difficulties about people meeting their younger or older selves and “history” being rewritten that by the close it’s tied itself up in a chronological shape a pretzel might envy. (One must expect there will be a flood of dissertations from die-hard fans disentangling all the twists and proving that they all make perfect sense, at least theoretically—as Schwarzenegger’s T-800 is fond of saying.)

But whether the plot is comprehensible is of little moment to Taylor, who follows the same pattern he did in “Thor: The Dark World” by tossing in a non-stop succession of big action set-pieces designed to deflect viewers from caring much about coherence. Are things getting a mite murky? Just stage another terminator-vs.-terminator fight, or terminator-pursuing-humans chase, or episode of vehicular mayhem (in one case involving a bus tottering off the edge of a bridge), or massive explosion—and hope that nobody notices. The entire picture is nothing more than a chain of such sequences, a sort of theme with variations in which the variations grow increasingly tedious because the villains are never really finished off and invariably return for another set-to (there’s that regeneration problem again). And even when all seems to have turned out fine in 2017—meaning that past and future have “unalterably” changed—the filmmakers can’t resist a code that suggests otherwise. People may die, and terminators can be boiled down to nothingness, but the franchise must live on.

One does have to give Schwarzenegger credit for having some fun with his T-800 character, bringing a bit of sorely-needed humor to the proceedings. One could simply say that he’s always been better playing a robot than a human being because his acting talent is so miniscule, and that’s probably true; but it doesn’t change the fact that he’s occasionally a hoot here. Otherwise the cast don’t add much to the effects. Neither of the two Clarkes, or Courtney, will efface memories of their predecessors in their roles, and apart from the stone-faced Lee almost nobody else gets much screen time (Courtney B. Vance makes what amounts to a cameo as a Skynet executive). But as usual J.K. Simmons is a refreshingly real presence as a cop in 2017 who’s met Connor and Reese before. On the technical side the picture is a thoroughly professional job, with Neil Spisak’s production design, Aaron Hayes’ art direction, Roger Barton’s editing and Kramer Morgenthau’s cinematography all top-notch—the latter especially impressive since he was hobbled by working in the 3D format. And the effects are sleek and superior down the line. Lorne Balfe’s score, however, is hideously bombastic, especially when heard in an IMAX room.

“Terminator: Genisys” does make one valid observation during a stopover in a 2017 hospital, where it’s noted how pathetic it is that people have become so tethered to their electronic devices that their faces are constantly staring at screens rather than engaging their fellow humans—something that makes the Genisys takeover possible. One wishes that viewers would take the message to heart, though that’s not likely. But it also points up how sad it is that Hollywood moviemakers have gotten so enamored of putting together special effects shows that they’ve forgotten how to instill some real humanity in their films. The result is too often a behemoth like “Terminator: Genisys”—another movie so crammed with visual razzle-dazzle in the service of empty, repetitive action that long before it ends, you feel exhausted by the excess.