There's a noticeable temperature shift when the sun begins to set and casts shadows over the 2016 Tesla Model S P90D as we set across the serpentine-like Angeles Crest Highway with Autopilot engaged. It's a pleasant setting, but tonight things wouldn't go our way.

Tesla's Autopilot system worked, somewhat, as we snaked our way through the Southern California mountains. The calm and buttery-smooth demeanor delivered by Autopilot on the highway made it easy to forget Tesla is still beta testing the programming. Yet it was infinitely more nerve-racking after a couple near misses along the mountain road. It's easy, then, to think this nail-biting ride would end in a catastrophic bang as we flew off one of the road's massive cliffs. It didn't. Instead, it ended with a whimper, with the car locked like a bank vault atop the radio tower-dotted Mount Wilson, leaving us in the colder-by-the-minute night—for five hours.

At the mountain's crest, right before sundown, we looked out at the Los Angeles skyline far below, staring at the city through the haze and falling sunlight. "It's beautiful," said my wife. I agreed, not knowing we'd be staring at that view for the next few hours. "We should've brought jackets," she continued, as the chill from earlier became almost too cold for our Californian blood. "I've got mine in the car if you want it," I said as I began walking toward the Tesla.

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As I got close to the car, the normally punctual array of electric whirring that usually happens when the key fob gets within range was nowhere to be found. I retrieved the fob from my pocket and depressed the unlock button. Nothing.

For the next 45 minutes, we engaged in the silliest key-fob postures, trying to find one that would get us into the locked $145,200 electric car—the one with flush door handles and no keyholes. The fob went under our neck, pressed up against our carotid arteries. Zilch. We walked a few yards away, turned, and did our best "Zoolander." Nothing again. Minutes pouring over the car's exterior looking for a manual-unlock feature felt like hours as nothing but frustration occurred. Compounding our annoyance, cell service was almost non-existent. Only by walking 200 yards down the road were we able to connect sporadically to the outside world.

An hour passed as my wife searched the Internet on my phone for a possible solution; her phone was locked in the car. She eventually found that getting locked out of a Tesla is a fairly common occurrence, one of the many issues plaguing the startup automaker, and owners have a handful of workarounds to get into the car when locked out.

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We tried almost every suggestion relayed on Tesla's forums, to no avail. Sadly, there is no Control + Alt + Delete to aid in rebooting the car's systems. Nor is there an analog way to enter the Model S. We gave up searching for a solution, and I walked farther down the road to find more steady service and connect with Tesla's representatives and engineers at the company's central command in Fremont, California.

My first two phone calls dropped almost immediately. After walking in circles as if I was in a Verizon Wireless commercial from the late 2000s, Tesla was finally informed of our predicament. After a brief and slightly garbled conversation, they said they would get back to us with possible solutions. And with that, we were once again left in the dark, alone with our imaginations.

Texting became the only routinely successful method of conversation with Tesla's engineers. First, they attempted to remotely access the car through its over-the-air update system. Minutes passed with no luck. They then instructed us to try a series of key fob movements around the car that supposedly helps signal reception between it and the car. These, like the first solution, didn't work. After two more potential fixes failed to produce a result, Tesla's people told us to give them a little more time to try another solution. They didn't disclose what this entailed, but at this point, our confidence was pretty low. Thirty minutes later, a text came through; the last solution failed and roadside assistance was on the way to either manually unlock the car or provide a flatbed.

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Two hours of nervous laughter, listening uneasily to sounds of what our minds tell us are wolves, bears, or bigfoot passed without incident. At midnight, the tow truck driver reached the top of the mountain after what he called "a terrifying ascent." Five minutes later, the Tesla's door is open with help from a balloon and a glorified stick. Score one for the Neanderthal solution to a utopian-electric problem.

At 12:30 a.m., we finally reached the smooth and well-lit 210 highway and left Angeles Crest in our electric wake. Exhausted and not looking forward to going to work the next day, we could barely keep our eyes open as the worried adrenaline wore off. For nearly 90 percent of the way home, Autopilot was engaged and did an admirable job of keeping us out of the guardrails.

Tesla is flummoxed by what happened. Its engineers could only infer that the electromagnetic fields surrounding the radio towers at the mountain's summit caused interference between the key fob and the car. The following day, Tesla sent a repairman to replace and reprogram the fob—it still wasn't working properly.

Regardless of the cause, we could have avoided this entire misadventure had Tesla included some form of manual override for the proximity fob and retractable door handles—perhaps a keyhole and removable key in the fob or some way to unlock the car by entering a code. Surely, Team Elon Musk could come up with a solution that lets the owner get inside manually without needing a tow truck driver's tools.