The story that this museum’s security system was disabled via a deliberate power cut, is utter nonsense. The only thing the power cut did, was putting off the street illumination. Advanced security systems have a no-break installation securing the continuation of electric power. Judging from the video the burglar-resistant glass of the display case had interlayers of PVB (Polyvinyl butyral). Glass always breaks (even in a Tesla car). The interlayer should be able to resist attacks for quite some time. PVB, however, is flexible and can be cut by an axe (in this case) or knives. Burglar-resistant glass offers a lot more resistance time when the interlayer is made of polycarbonate. There’s a lesson to be learned for all museums with very valuable collections. They all should audit the structural resistance of the outer shell of the building, the structural compartmentation of the building (burglars should not be able to move through the building without being confronted with delaying compartments), and the construction of display cases.