Metal shavings inside plenum , anyone came across this before ? 2 spark plugs are bent , engine won't turn

 

That engine is blown sir. Possibly a rod knock that said no more.
Those metal shavings are parts of piston/valves and heads, this happens when the valves get destroyed, nothing stops them from from entering the manifold
This is why the engine wont turn, you'll need a new engine.

 

I suspect the galley gasket failed resulting in too low oil pressure, which destroyed the crank bearing and the piston smacked the spark plug and head.
If you have a G37, you really need to have an oil pressure gauge to prevent this.

I'm sorry this happened to you. A failing oil galley gasket is just about the only bad thing about the VHR engine

 

Thought so , thank you very much for your quick response , was just curious how the metal ended up there