Checking a wire for an open means checking both ends of the wire for continuity. If there is no reading then the circuit is "open" and the energy flow is interrupted. The wire should be disconnected on one end before checking for open.
As far as your issue goes, it sounds like a "Neutral Safety Switch" problem. If the shifter is not fully in PARK or if the clutch is not all the way in (manual trans), the engine will not crank. but if you already do this then check the switch to verify if it works anyways.