OK,thanks for your feedback. However, Your example is the core puzzle of the second level. I hope players could experience the joy of "discovering a solution to a puzzle that they believe cannot be solved".
But I can give you a little hint.
First, if you read the instruction before level2, you could discover that player need to push the train carriage.
Second, if you go to the map on the left side of the carriage, you could find another door activator which is outdoor.
Third, the instruction before level1 notices player this train is driven by magnetic