NAIROBI, Kenya — It was always about more than a single election.

Kenya’s judiciary, which has battled for years to establish its independence, asserted itself last month with a decision that surprised the world, nullifying a tainted presidential election and demanding a repeat to prevent fraud.

It was a moment of democratic triumph, of an independent court defending a young constitution — or at least it seemed like that, until the last minute.

This week, for the second time, Kenyan activists and lawyers pinned their hopes on the Supreme Court, which agreed to hear a petition on the credibility of the new election. Chief Justice David Maraga issued an order requiring all judges to work on Wednesday, despite a hastily declared public holiday, and he promised a 10 a.m. hearing that might make or break the next day’s poll.

But when the time came, only one of the other six judges showed up. Mr. Maraga, sitting alone on the bench, announced that, lacking a quorum, the hearing couldn’t happen.

And that is how this battle over Kenya’s democratic institutions ended: abruptly, because not enough judges had come to work.

“It’s an anticlimax,” said Haron M. Ndubi, the lawyer who filed the petition. “This is when we were hoping to see the judiciary’s strength play out. We had just started having hope in an independent, strong judiciary, and then suddenly it’s undermined.”

“It’s like opening and shutting the case on freedom,” he added.

His frustration reflects a wider reckoning going on in Kenya, where many people are asking themselves how, after the national trauma of election violence 10 years ago and the enormous steps that have been taken since then, they have ended up, yet again, here — in a muddled election, at the mercy of their leaders, praying for peace.

On Thursday, the country will vote again for president. But the main challenger, Raila Odinga, insists that he will not participate and urged his supporters late Wednesday to boycott the vote, raising the dangerous prospect that millions of his supporters will not acknowledge the outcome.

Only a month ago, the world was lavishing praise on Kenya for the strength of its nascent democratic institutions. Supporters of Mr. Odinga, who lost the August poll by 1.4 million votes, embraced a second chance at a win. Even the incumbent who had been declared the winner, President Uhuru Kenyatta, struck a statesman’s pose at the court’s decision.

“I personally disagree with the ruling that has been made today, but I respect it,” he said in a national address in September.

But the euphoria turned cynical and the acrimony on both sides grew more heated. Mr. Odinga announced his withdrawal from the race, insisting that a new poll run by the same election officials could never be fair and credible. His supporters, and many Kenyan political observers, worried that his withdrawal would leave his six million supporters feeling disenfranchised.

Meanwhile, election officials faced threats and intimidation. Last week, one commissioner fled the country and resigned from New York, citing death threats. The same day, the man in charge of the election, Wafula Chebukati, admitted that he couldn’t guarantee that the poll would be credible. On the eve of the Supreme Court hearing on Wednesday, the bodyguard of the deputy chief justice was shot by an unknown gunman.

In the days before the new vote, Mr. Odinga and Mr. Kenyatta refused to speak to each other. Nearly two dozen foreign ambassadors essentially threw up their hands in a joint statement, asking yet again for dialogue and pleading with Kenyans “to choose Kenya” and get through the coming days in peace.

The closer Kenya came to the repeat election, the heavier the question felt: After all that has happened, would any poll be considered credible? And if it wasn’t credible, what then?

“Our political system still does not deliver what could cool down the temperature of politics in Kenya,” said Bobby Mkangi, one of the nine experts who drafted the new Constitution that Kenya adopted in a national referendum in 2010. “Even in the Constitution I participated in, I think we didn’t get the state right.”

The problem, he said, was a winner-take-all-system in which the nation’s democracy fell captive to ethnically driven politics: The bigger the ethnic group, the more likely it is to capture power, especially the presidency.

It comes, Mr. Mkangi said, from “a collective kind of thinking, of ownership and belonging,” one that can be positive. But in politics that collectivity can make it hard for Kenyans from smaller groups to feel included in government. Marginalization, he said, is the real root of this year’s electoral crisis — one that no repeat election, no matter how credible, will solve.

“The elections are just a symptom,” Mr. Mkangi said. “The real question is addressing the political system and trying to come up with something that is more equitable to all, so that at the end of the election you don’t have certain ethnic communities feeling alienated for five years.”

Kenya’s electoral problems stretch back decades, but the most serious crisis came in 2007, another election Mr. Odinga lost. That presidential poll ended with a disputed tally, a media blackout and a nighttime swearing-in of a hastily announced winner, President Mwai Kibaki.

Widespread violence followed, as Kenyans took to the streets and clashed. More than 1,100 people were killed and hundreds of thousands displaced. The unrest lasted several weeks, and much of it was perpetrated along ethnic lines.

The current president, Mr. Kenyatta, and William Ruto, the current deputy president, were later indicted by the International Criminal Court for their role in fomenting the violence, but the cases against them were dropped after the government refused to cooperate with the prosecutor’s office and witnesses disappeared.

The 2007 crisis came to an end when the winner, Mr. Kibaki, agreed to share power with the opposition — the only national example in postcolonial Kenyan history of an alternative to the winner-take-all system.

It felt, to many Kenyans, like a new era.

“We were in a very positive spirit, even though we had not solved many of the structural issues that had led to the crisis,” said John Githongo, an anticorruption advocate and the publisher of theelephant.info, a website for Kenyan political debate. “We had a coalition government, and that led to optimism. But the optimism was derived from a tremendous sense of relief.”

That relief accomplished a lot: A new Constitution was written. Power was decentralized from the national government in Nairobi and “devolved” to counties across the country. Many hoped that greater feelings of inclusion could be fostered by bringing government closer to the ground.

But there were still structural problems — among them, how to run elections. The 2010 Constitution laid the groundwork, and the elections law provided many of the details, but elections were still a work in progress in 2013, when Mr. Kenyatta and Mr. Odinga faced off. Mr. Odinga lost then, too. And then, too, he challenged the results, but the Supreme Court rejected his arguments.

That didn’t mean there were no legitimate problems with the vote, according to Mulle Musau, the national coordinator of the Elections Observation Group, a domestic elections watchdog. But few people wanted to push reform too hard.

“Kenyans were still very raw from what had happened in the postelection violence,” he said. “There was much more of a ‘let us accept and move on’ philosophy.”

In many people’s eyes, that philosophy continued while Mr. Kenyatta curtailed some of the promises made in the Constitution. He restricted the press, reined in civil-society groups and expanded the powers of the military and the police. Kenyan activists contend that Mr. Kenyatta’s first term began to erode the nation’s young but hearty democratic institutions.

That is one reason Kenyans were so surprised — and many of them delighted — when the Supreme Court nullified this summer’s presidential election. It was the strongest example of any institution demanding accountability and transparency — and during an election, no less.

“That’s part of what makes this a really defining moment,” said Nanjala Nyabola, a Kenyan lawyer and political analyst. “It’s bigger than just who wins the election. It’s a moment Kenyans are being asked to decide who we are and what we stand for. And people are using the law. Thirty years ago, nobody would’ve tried.”

Now, though, Bilman Emtabi, a 26-year-old “peace worker” from the Eastlands neighborhood of Nairobi, said he wasn’t too worried about the law, or heady ideas of enfranchisement. The election “is a sad story,” he said. “Kenyans today are divided in two — those who are hopeful of an election tomorrow, and those who are not.”

“For me, whether there’s an election tomorrow or not, I don’t care,” he said. “I just want peace.”