get the topend off and lets see carnage pics, if the piston just seized and not shattered, you should be good with just a bore/hone/piston
but we need to figure out what caused this, is the oil injection on and working, is there good oil in the tank, made for injection???
if injection is deleted, you do know the oil needs mixed with the fuel 32:1 ratio
tell us more about what, when, where, how and we'll try to figure out why ????