When uBeam made its splashy debut in the tech press in 2012, its premise sounded too good to be true. The Los Angeles–based start-up claimed it was pioneering a new system that could charge devices wirelessly from meters away, but how? The start-up hadn’t brought a product to market, so critics tried doing the physics themselves and came up short. Meanwhile, a rich roster of investors, including Andreessen Horowitz, Founders Fund, UpFront Ventures, Yahoo C.E.O. Marissa Mayer, and Mark Cuban (who called uBeam a “zillion-dollar idea”), pumped tens of millions of dollars into the company, turning its twentysomething founder, Meredith Perry, into a star. In an attempt to quell critics, uBeam declassified information last year to satisfy skeptics who criticized uBeam’s technology as either ineffective or unsafe.

Perhaps nobody would know uBeam’s products and technologies better than one of its engineers. And an anonymous engineer who has since identified himself as the company’s former V.P. of engineering, Paul Reynolds, has come forward with a series of blog posts about uBeam. In a set of posts on a blog titled “Lies, Damn Lies, and Startup PR,” Reynolds comes out and says uBeam, the start-up at which he worked for more than two years, is more or less peddling snake oil. Or, as TechCrunch’s Josh Constine puts it, uBeam has been accused of being the “next Theranos.” (Theranos, as you might recall, is the $9 billion blood-testing company whose reputation was all but obliterated in the past year, in the wake of a series of Wall Street Journal reports asserting that its much-hyped technology doesn’t actually work.) A request for comment from uBeam was not immediately returned.

Reynolds is candid about uBeam’s alleged failures in his series of blog posts, which range from detailed explanations of math and physics concepts behind the technology that uBeam and its competitors claim to be building, to why he joined the company in the first place. Among other things, Reynolds asserts that uBeam’s technology simply does not work, and that’s why the company won’t hold a public demo of the wireless-charging technology. “While in theory it may be possible in limited cases, the safety, efficiency, and economics of it mean it is not even remotely practical,” he writes. There’s also been executive shifts at the company; both the C.F.O. and C.T.O. have since left. To boot, Reynolds is critical of the “lazy” tech journalism that perpetuated uBeam’s presence in the media, and he’s not complimentary of Perry (who was on Vanity Fair’s 2015 New Establishment list), either. “You know, we all love the idea of an underdog who’s a scrappy little fighter and in the end proves the big dog wrong. It makes for a great film,” he says. “But here in the real world, most of the time that scrappy little dog is just plain wrong.”