Push the blue button then leave.
I bet the blue button is a cheeseburger dispenser...
Two items appear under the desk. One seems to be a golden ring of some sort, and the other a hammer, with a light-blue hammer head. The light-blue hue doesn't seem to be from paint, so maybe it's made of a special material...
Whats on the underside of the table before you leave, go check.
You check under the desk; There seems to be some sort of switch under here, along with a panel; You also note that the panel isn't
locked, just closed.
Shoot at the door again if possible.
You pull the trigger on the shotgun, but there's no ammo inside it. And you sure aren't dragging any ammo around with you. I guess you wasted your only shot blasting a door. Oh well, you keep it for later.