Much medical lab practice includes running known test samples through the process regularly to check the test. They skipped a lot of that. Many things can potentially go wrong. They did. Expired reagents, freezers at wrong temperatures, failure to do regular maintenance, patient tests run on machines that were reporting errors... Some of the technicians hadn't completed medical technician training, but were doing complex tests. The summary: "Overall, over 21% of QC samples on all devices had values greater than 2 SDs". So many results were way off, and they weren't catching that.
Those are for standard tests on standard machines. The results for Theranos' "Edison" machine were worse. As in more than 10x more variation than standard techniques.
This isn't even the FDA. This is the Center for Medicare Services checking up on a company to which they paid a lot of money.
WSJ: "“This is the first time that we’ve actually seen data from the Theranos instrument, and it’s as bad as one would have worried it would be,” said Stephen Master, associate professor of pathology at Weill Cornell Medical College in New York. “Based on this data, it’s hard for me to believe that they went live with this instrument and tested patient specimens on it.”
"The inspection report said Theranos didn’t notify doctors treating patients potentially affected by the erroneous results until mid-November, or seven weeks after the inspectors first identified the problems."
"The lab directors during the period of the survey no longer hold any position within the lab. The new lab director..."
This looks like the "move fast and break things" crowd trying to run a medical lab.