How to make a U-turn with a TGV

Another one day trip to Brussels, that started well in the morning. Still quiet in the streets, except joggers, delivery services and some other early birds (see photograph).

When seated in the train back, a delay of half an hour was announced. But when the train started to move, it left Brussels station in direction of Amsterdam ... and not Paris. What the heck was going on ...?
The mystery was solved quickly by the train assistants: there was a problem with the driver's cabin door and staff didn't succeed to open it. So the decision was to use the driver's cabin at the rear and have the TGV making a big loop around Brussels, before then heading towards Paris.