The funny thing was — when he finally got off the nightmare train after 45 minutes stuck between stations without electricity — the subway cell service worked just fine.

That’s how Michael Sciaraffo, 36, was able to blast out a Facebook post detailing his harrowing Monday night F-train ride. Soon, the post was ricocheting around the world along with other tweets, videos and cries de coeur of riders from the stuck F, the latest and maybe most vivid example of NYC’s recent subway woes.

The subway nightmare

At about 6:20 p.m. Monday, an F train lost power due to mechanical problems and came to a stop between West 4th Street and Broadway-Lafayette. Lights and air conditioning along most of the train winked off. And though it quickly became clear that something was seriously wrong, commuters say that the voice over the loudspeaker originally insisted that there was just “train traffic ahead.”

Sciaroffo, an analyst for the Parks Department who has been riding the subway since high school, says conditions were worse than anything he’d ever seen. Temperatures rose so high that people began to take off clothes — nearby passengers held a coat around a woman so she could take clothes off but remain decent, “like at a beach,” he says.

Riders did what they could to get air, cracking open the windows and wedging books, umbrellas and Altoids tins into doors to get even a breath of wind from passing trains.

Some people were “distressed or having panic attacks: people got them seats or spots by open windows,” wrote software engineer David Taylor, 30, who was also stuck on the train.

Those who kept their cool began “trading stories of subway nightmares,” says Leslie Engel, 40, a writer heading home to Windsor Terrace. Conversations passed back and forth about times the MTA had made people late to work, “how it affected their lives.” Boos greeted the conductor’s obfuscations.

According to the MTA, crews ultimately powered up the train enough to get into Broadway-Lafayette, but the ordeal wasn’t over. For approximately five minutes, the doors stayed shut because the train had overshot the station, meaning the doors couldn’t be automatically opened.

“People flipped out,” said Sciaraffo — screaming for help, banging on the doors. Some tried to pry the doors open. Someone had traced the words “I will survive” into the fogged over glass, now in view.

For Sciaroffo, the experience was “the last straw” and, he hoped, a turning point in what New Yorkers demand from the MTA.

That should mean a complete re-imagining of the MTA, he said, from the way it communicates to the way it does track work, to the snail-like pace with which it is approaching signaling problems, to the way dollars are spent on its capital plans. But mostly, someone needed to be held “accountable.” And he said that the buck must stop with Gov. Andrew Cuomo, who controls the MTA.

It’s a complex challenge, but one that needs fixing

The MTA’s problems are vast and complicated, including aging signaling systems combined with ancient cars that are being too-slowly replaced — such as the model of F train that turned into a sauna Monday night, R56s that date to the mid-1970s.

This creaking infrastructure plus an unwillingness to devote sufficient resources has resulted in delays more than doubling since 2012, amid mounting frustration and crowding.

It was all enough to bring Sciaraffo out to the Columbus Circle Starbucks on his lunch break Tuesday afternoon, where he held a series of interviews with news outlets including an impromptu TV news conference. The unlucky straphanger has a political background, with stints working for Hillary Clinton and the New York City Council, and he was eager to rally political energy toward some measure of accountability for what is becoming an unacceptable situation underground. For decades, politicians have largely avoided responsibility apart from studies, contests, committees, and tepid plans such as the one Cuomo announced last month. Maybe a few more nightmare trains and something would really change.

Because, of course, change is possible underground: as Cuomo trumpeted this January, in announcing Wi-Fi and cellular connectivity completed two years and a year ahead of schedule, respectively.

That service worked just fine as a sweaty Sciaraffo got on the B train on the opposite platform and uploaded his Facebook rant. By the time he got to Brooklyn, the post was well on its way to going viral, hitting a nerve among riders for whom Cuomo will have to more seriously deliver.