NORTH ANDOVER – On Friday night, No. 16 Holy Cross was well aware of the danger Merrimack presented in front of a raucous home crowd in the season opener for both teams. A year ago, Merrimack went into Fitton Field and beat Holy Cross, so the Crusaders weren’t going to be caught off guard again. Behind 502 yards of offense, two interceptions and a blocked punt for a safety, Holy…