If the captain was armed he could have at least tried to shoot the lock open on the door. Like on submarines we need to start arming all captains.
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I bet that door is engineered like a safe with multiple bolts sliding out into the door jam all the way around.
According to the youtube video it has 3 electrically activated deadbolts and the door itself is rather robust.
CC
There are videos you can watch describing the Airbus door.