PHILADELPHIA -- With her controversial blood-testing company under intense federal scrutiny, Theranos chief executive Elizabeth Holmes took the stage before hundreds of medical laboratory experts on Monday to present a new blood-testing device and bat down questions about a series of blunders that have thrust the company into crisis.

Holmes, who spoke at a meeting of the American Association for Clinical Chemistry, avoided the long list of regulatory and credibility problems that face the company she founded in 2003, when she was 19. Theranos has experienced a rapid fall from grace, with federal regulators banning Holmes from owning or operating a lab for two years. After a host of operational lapses, the company voided then corrected two years of patients’ results from its proprietary Edison technology.

Holmes pitched her presentation as an “inflection point,” as she works to forge relations with the scientific and medical community.

“We fully understand ... that we have a lot of work to do to engage with this community,” Holmes said. “I can tell you, I wish that I had started earlier.”

Theranos promised to revolutionize the medical industry with technology that could process a panoply of tests using just a few drops of blood from a finger prick. Now the company is facing a federal criminal investigation into whether it misled investors, and its major partner, Walgreens, has ended the relationship.

The Silicon Valley startup said Holmes’s presentation would finally pull back the curtain on its science and data for scrutiny.

Stephen R. Master, director of the central laboratory at Weill Cornell Medicine, who sat on the panel that questioned Holmes, said the revolutionary promise of Theranos’s technology was not supported by the data she showed on Monday.

“The evidence you presented fell far short of that, so how should we think about it?” Master asked, to applause.

Holmes replied that the presentation focused on the architecture of the company’s new technology and was an introduction to the invention.

Her talk — touted by a public relations firm as a “breakthrough presentation” and filled with videos of robots moving liquids with pipettes — focused on the technical specifications of the new device, called miniLab.

The presentation included data generated by Theranos on several blood tests, but did not include any peer-reviewed data.

The company has submitted its data on a Zika diagnostic to a journal and to federal regulators. Since last fall, Holmes has promised to publish its data in peer-reviewed journals.

Scientists’ reactions spanned a wide gamut and 583 questions swamped the panel tasked with a 45-minute Q&A with Holmes and three company representatives.

Some scientists expressed frustration that the presentation didn’t elaborate on any of the company’s lapses. Others said the data provided was a good start, but pointed out that the technologies that are miniaturized in the new device are not unique.

Geoffrey Baird, an associate professor in the department of laboratory medicine at the University of Washington, said the presentation was an attempt to distract from the company’s troubles.

“This is not the science of Theranos that they were doing any clinical testing on,” Baird said. “This is theater, what we’re getting right now. This is not science.”

The line for the talk began to form more than an hour before Holmes was scheduled to go on stage, reflecting the considerable attention that has focused on the spectacular rise and fall of Theranos. Once valued at $9 billion, Theranos was for years a darling of investors and media. Holmes was compared to Apple legend Steve Jobs, featured on magazine covers and able to attract a slate of well-connected former government officials to her company’s board -- although there were noticeably few with deep expertise in laboratory testing or medicine.

Holmes’s presentation was punctuated by evidence of the caution the company is now exercising. This year, Theranos added a group of well-respected laboratory medicine experts to its medical and scientific advisory board. Holmes's presentation slides carried a footnote that the technology had not received approval from the Food and Drug Administration and was not for sale in the United States. In her introduction to Holmes, Patricia Jones, the president of the American Association for Clinical Chemistry, noted that hosting the presentation was not an endorsement of the company.

K.T. Jerry Yeo, a professor of pathology at the University of Chicago, said that the technologies presented were all well-known to laboratory professionals, and the Theranos’s only innovation was putting a variety of miniaturized lab equipment capable of multiple kinds of blood tests in a single box.

“This kind of a presentation, we have seen in one way or another with different companies, trying to make a smaller box,” Yeo said, noting that he could see a potential use for the Theranos device, but “the jury is still out.”

They only showed several “handpicked” tests, Yeo pointed out, and the data also don’t reflect how the device works in the real world, since it was all tested by Theranos.