Deborah prepared a mercury replica of the Argos Engine with the card inside. She likely used the 3D printer to accomplish this. This was placed inside the temperature-regulated case and stayed all cool and solid. That way, she could slip out the real thing way beforehand and didn't have to worry about it. The EMP deactivated the electronics keeping the case all nice and cool, so the mercury melted and vanished through the holes into the ventilation system. (If the EMP device was too far away, there simply was another hidden closer to the case,
for example inside the cake.
Counter this moooooove.