Electric vehicle startup Nikola Corp. finds itself facing scrutiny from shareholders and federal regulators following fraud allegations from Hinderburg Research. The short seller firm accuses Nikola, among other things, of staging a video where its hydrogen fuel-cell truck was driving itself. The company actually doesn't dispute that specific claim. This scandal has not only impacted Nikola's stock but forced its founder Trevor Milton to resign. And now it faces copycat allegations from Tesla.