Opendoor's stock has taken off like a rocket ship, leaving the new CEO with a lot to prove.Opendoor Technologies (OPEN -6.92%) received a warning letter from the Nasdaq exchange this May that it would be delisted because its stock price was too low. That set in motion a series of events that have turned the stock into a rocket ship, with the shares up over 1,600% in just the last three months. A big part of the story is the company's hiring of Kaz Nejatian as CEO. What does this really mean for investors?Th ...