Help with 60098 (not moving)

Hi guys. I just got a used 60098 Heavy-Haul Train. The train (mostly assembled, seems correct, including electrical components placement and connections) is not moving, despite both the remote control and the engine box blinking green. The remote control didn't require new batteries (blinks green when pressed); I changed them in the engine. After inserting new batteries, the engine box LED turns green when pressed (and turns off when pressed again). The remote control blinks green when I...