Can anybody explain this dead commuter-line train?

Wonderfitzig was among the people who had to hop off inbound train 156 on the Newburyport/Rockport Line train and get on another after the engine sighed its last and went to the great roundhouse in the sky this morning near River Works - after their train just sat there for 90 minutes or so.

He reports the conductors told people to walk down to a designated spot to cross, but all the doors were already open because the train lost its AC, so people just went out the nearest door to get onto the other train. Track-walking video.

The problems with that train, naturally, meant delays for the train behind it. Kelly Noonan reports:

Also - no communication to the train behind it (106) that was stopped to theoretically push 156. We stayed on the train after 156 was transferred and are now pushing 156. Zero communication throughout.