SPAX 901, here at Langhorne the next day, stepped in to pinch hit for 902 while reportedly a circuit board was replaced.

Update September 6 2018: I have been told the problem was with the battery, and was not mechanical but rather a training issue. Apparently the new engines have sensors that drop the pans in the event of a possibly dangerous power fluctuation. There is also a switch that controls whether the battery power is supposed to engage in the case of power interruption. One would assume when the train is in normal operation, the battery power switch is on and a momentary loss of power would result in the battery kicking in until the pan is raised again by the crew and power was restored. However, if the train were parked and unattended, there would be no one to raise the pan. While the pan was left up when the train was parked Friday evening, a subsequent power spike triggered the pan to drop and, with the switch left in the on position, the engine ran on battery power until it was completely drained. When the Monday morning crew tried to start the engine, they could not even get the system to reboot, so it was taken down to Wayne Electric, MUed to another engine and with the pan once again raised, allowed to recharge, and 902 was in fact running again that evening. However, since the trains are frequently left running during the summer and winter months to provide air conditioning and heating respectively, this could be a problem down the road.