Remove the connection plates on the lintels of the front and rear doors and install them again as shown in the figure.
Figure 1 Installing the connection plates
Use the spirit level and the plumb line to verify that the bottom line of the cabinet is horizontal and the front line of the column is vertical. If the cabinet is not horizontal, adjust the adjusting anchor by using a socket wrench.
Figure 2 Leveling the cabinet
Both the gap between cabinets and the vertical deviation should be less than 3 mm.