Regarding Azus and others' intention to seize his refuge, and even control him personally, Chen Xin was naturally unaware and did not even know that his refuge was being monitored.
But even if he knew, Chen Xin would probably not consider it worth his attention.
With the current thickness of 300mm nickel-chrome alloy armor steel door at the main entrance, even a modern army would need heavy firepower to blast the door open.
Such heavy firepower doesn't refer to heavy machine guns or rocket launchers, and mortars are inadequate as well—it would require genuine heavy firepower, at least armor-piercing bullets fired from the main cannon of a main battle tank.
Don't think it's exaggerated; during WWII, the front armor thickness of the main turret on Bismarck battleships was 360mm, the Hood battlecruiser turret was 381mm, and the Missouri battleship turret was 495mm...
