You flooded it.

The fuel is uncompressable. Once it has displaced the air in the engine it becomes very difficult to cycle the piston. (And overpowers the glo-plug's ability to ignite it). You could have snapped the piston rod. If this happens again, remove the glowplug and use the starter motor to cycle out the fuel (Tipping the engine if possible so it can slop out the plug hole).

Try starting it at 1/3 throttle.