NEW YORK—A recent power outage that disrupted half of New York City’s subway system for several hours and stranded hundreds of passengers was likely caused by someone accidentally pressing an “Emergency Power Off” button, according to investigations released Friday. Outside investigators looking into the disruption on the night of Aug. 29 said there was a “strong possibility” that the button was accidentally pressed since the plastic guard designed to prevent accidental activation was missing, according to a pair of reports released by New York Gov. Kathy Hochul. The unprecedented breakdown affected more than 80 trains, giving a black eye to a sprawling transit system that has since been hit with flooding from the remnants of Hurricane Ida. Hochul ordered a full review of operation control centers across the Metropolitan Transportation Authority to identify and fix potential weaknesses. “New Yorkers deserve absolute confidence in a fully functioning subway system, and it …