Repairing holes in walls or mollys for tv mount

Long story short, I tried to locate studs in my bedroom wall using a stud finder so I could mount a TV. Turns out there's nothing but plywood and styrofoam in my walls. I now have two holes that I need to repair/conceal or use. Anyone used the plastic mollys that spread open to mount a TV(I've tried the kind that screw in but they just chew up the wood)? If I can't use these existing holes, any suggestions on how to repair or conceal the holes? I know wood filler would work but I was hoping for something more inconspicuous and less noticable. Thanks.