(CNN) -- A day after Sunday's 35-minute power outage during the Super Bowl game in New Orleans, officials were vowing to fix whatever the cause may have been, but no one was saying just what that was.
"We're going to work very closely with SMG to get to the root of the problem," said Charles Rice, president of Entergy New Orleans Inc., referring to the company that manages the dome. "We both made excellent preparations for an event like this, and then the system worked the way it was supposed to work."
"We've spent millions of dollars upgrading our equipment, including our electrical feeders, and we've never had this issue before," said Doug Thornton, an SMG executive who was in NFL control at the time of the incident. The interruption in service occurred in a substation that supplies the stadium with power, he said. A piece of equipment in the substation "detected some abnormalities and it did what it was supposed to do -- it opened a switch, basically a breaker, which shunted the power that we were receiving from Entergy and de-energized the building."
He noted that electricians and electrical consultants were on site and pitched in immediately.
A fire alarm that was hit prior to halftime appears to have had nothing to do with the outage, nor did the halftime show, Thornton said. The halftime presentation was run on generated power, "which means it was not on our power grid at all," he said.
Any electrical issues identified in the probe will be addressed, he promised. "These are fixable problems," he said.
"Obviously, for me, it's a disappointing moment, but when you're relying on systems, it's not a human error, it's an equipment error. We'll get to the root cause of it and we'll find out what it is. It's very disappointing."
NFL Executive Vice President Eric Grubman praised the fans for remaining calm. "They acted with the belief that the game was going to come back on, just as you or I would have acted in their seats, and that's what you and I did."
Though the investigation has just begun, "There is no indication at all that this was caused by the halftime show, absolutely none," said NFL Commissioner Roger Goodell, referring to Beyonce's power-packed performance. "That is not the case from anything we have at this point."
The company completed upgrades to the stadium's electrical equipment on December 21, but that may have had nothing to do with Sunday night's problem, said Entergy spokesman Philip Allison. "Since then, we've had three major events -- the New Orleans Bowl, the Panthers-Saints game and the Sugar Bowl -- "with no issues."
On Monday, CBS aired video shot from inside a stadium control room as the outage occurred.
"All right, we lost lights," says a man as the room darkened.
Moments later, a man says, "Frank, we lost the A feed."
"What does that mean?" he is asked.
"It means that we have to do the bus tie."
"What does that mean?"
"It means about a 20-minute delay."
The CEO and director of research for Zpryme, a market intelligence and analysis firm for the utility and smart grid industry, said someone appears to have made a mistake in their estimate of how much energy the building's electrical infrastructure could handle.
"Someone made that decision not to invest, saying, 'We can handle this,'" said Jason Rodriguez. "Come to find out that their load was just much higher than anticipated."
He continued, "You can say it's the electrical infrastructure but, at the end of the day, there's a human component to it, a decision that had to be made."
But Bill Squires, a sports facility consultant, was not persuaded anyone was to blame.
"I would be very reluctant to ever point a finger, knowing what I know now, at an individual; I just think it was one of those things," he said. "I've got to believe that those guys do the preventive maintenance."
Besides, Squires said, the outage was no more than an inconvenience. "Nobody got hurt; everybody was safe."
And James Fama, vice president for energy delivery at the Edison Electric Institute, said the system appears to have worked well, given that the lights came back on and the circuitry was not damaged.
"The bottom line for any utility or any electric planner would be -- protect your equipment so that you can re-energize it. And it appears to be exactly what happened."
CBS, citing ratings figures from The Nielsen Company, said Sunday's game between the 49ers and the Ravens reached a total of 164.1 million viewers, making it the most-viewed show in U.S. history. Figures were tallied from 6:32 p.m. ET until 8:41 p.m. ET and from 9:11 p.m. until 10:47 p.m.
The average number of viewers was put at 108.4 million, which ranked it third.