Theranos Inc.’s 15-year quest to revolutionize the blood-testing industry met with the latest in a series of crippling blows in March when the Securities and Exchange Commission charged the Silicon Valley diagnostics firm with conducting an “elaborate, years-long fraud.” The SEC accused the firm of deceiving investors into believing that its portable device could perform a broad range of laboratory tests on drops of blood pricked from a finger, when in fact it was doing most of its tests on commercial analyzers made by others....