A teenager is facing charges for what MBTA Transit Police are calling a "foolish, dangerous stunt."Patrik Finnerty, 19, of Braintree, was on the northbound platform at Andrews Square Station when he climbed down onto the tracks, crossing over and climbed out onto the southbound platform.An arriving train was forced to perform an emergency stop and prompted authorities to cut power to the tracks in both directions.He was charged with walking on railroad property and disorderly.MBTA Transit Police said Finnerty failed to show up to his arraignment Monday and an arrest warrant has been issued.