since they don't speak about opening doors or testing attributes for opening doors. And a monster therefore allso uses his attack or move action to open/close the door. so they use the attack/move action as an….action.
Monsters do not use attack/move actions to open doors. They use the "Open/Close Door" action to open doors, same as a hero does. In the English rulebook, this is explained on page 11, I'm not sure if it's the same in Dutch.
Bottom line: neither Frenzy nor Dash allows a monster an additional attempt to open a door. Neither "Attack" nor "Move" actions may be used for this purpose. An "Attack Action" can ONLY be used to make a BASIC ATTACK (It can't even be used to make a special monster-specific ability that includes an attack, those are "Monster Actions") and a Move Action can ONLY be used to perform a Move.
FYI: If the quest requires an attribute test to open a door, that's a "Special Action" whose consequence is that the door ends up getting opened. The details of which would be spelled out in the quest rules themselves. You still can't use Attack or Move actions to do these things.