1st your model warped thous the curved up edges on your model cube.
This could be because your first layer was incorrect, of the air flow in your 3D Printers environment.

2nd you will again note on the cube that you have layer that are not symmetrical,
This could be cased by the Z-Axis couplers are not spinning true.
you could add a single wrap of electricians tape on the lead screw end then press the lead screw into the coupler. this will give the couplers a smoother turning radius.

I would also ask you at what speed and layer height did you print the model?