06 Dodge Ram 1500 4.7l V8 No Crank No start

I’m at my wits end with my truck. Parked it
one night after running to the grocery store
and the darn thing won’t crank or start. I
tested the starter relay and I can feel it
working. When I turn the key over I hear rapid
clicking, like a machine gun. I had a mobile
mechanic come take a look and he thinks I
flooded my engine and need to replace my
spark plugs but I’m very skeptical. I know it’s
possible to flood a fuel injection engine but it’s
not very easy either. Aside from pulling a
spark plug taking a whiff what could be my
problem?