provided that if your compression is still good, screw out the plug, rotate the flywheel till piston position reach top. when its there, try to move the flywheel again back and forth with little motion.if the piston doesnt move(at top postion) when u apply movement to the flywheel, then its the conrod.
Serpent S411 TE : ready to race
Tamiya TA05 VDF : sleeping mode
Align 450 sports v2 : tick-tock in progress