Blow by without question. The remaining rings in first pic are still wedged in grooves. Overheated without question. I'm sure the underside of piston dome is charred, but a pic would be nice too. That clip came out and seized it. The bottom of cylinder broke off when you had to force it apart becasue of the wedged circlip. 400 degrees is danger zone and you exceeded that by how much total? Looks to have reached 400 degrees more than once. Everything in pics is toast but I hope rod and crank aren't.