Flatten a surface

After designing and 3D printing a part, I needed to move some of my mounting holes. I moved them a few mm in various directions on my 3D model. The end result was that the rear surface that the holes went through, has warped the flat surface on the rear of the holes. The holes were through a wedge shape and moving them meant the holes were now through a different thickness of the part.

Is there a way to re-flatten a surface of a 3D object that gets distorted?

Depending on the shape of the body, you could cut it, either by using a plane and split body tool, or by extruding from a sketch and cutting it with that.

You could also try deleting the holes at their original plce, and creating new ones at the new place, so their edges won’t blend the original body.