STAMFORD — A man who nearly sawed the hand off of a New York City businessman was found guilty of first-degree assault on Monday, but jurors were unable to reach a verdict on burglary and home invasion charges, which means that the state has the option of seeking a retrial for those offenses. Cesar Olivero attacked the man at his ex-girlfriend’s apartment in what appeared to be a jealous fit of rage on June 25, 2015, according to police. The man who was attacked was out having drinks in White Plains, N.Y.