Welcome to iRV2.
Sorry you're here with problems .
I believe , I once worked on the type of outlet you're describing . they are used in thin walls that don't have room for a standard outlet box. Power cable goes in one end and out the other with no visible connections.
Is there any chance you could post a couple of pictures of what you've got , that might jog my memory as to how I got it apart.
Info on posting pictures is in the " FAQ " drop box , center of the dark blue bar under the Google search box.
I looked online but could come up with an image of the outlet as I remember it.