Fuel. Air. Spark. Need them all.
I think if the clutch or sidestand switch was faulty it wouldn't crank... check the wiring diagram on that one. My clutch/neutral/sidestand switches go to the ECU.
Push the start button and let it crank. Pull a plug from each cylinder, are they wet with fuel? If they are not you can check to see if you have fuel delivery by removing the airfilter and holding the throttle wide open while you crank after replacing the plugs or grounding them to the engine in some other way... you should see fuel spraying into the throttle body. If you don't see fuel you have a fueling issue, either the ECU isn't telling the injectors to fire or the injectors are firing but there's no fuel supply. With the pump and filter inside the tank, there are a few hoses in there, and they have been known to crack or pop off. Not sure on the 916 how to access, on my '97 SS everything went into the tank through the filler cap hole. The filler cap assembly had to be removed after the tank was drained to get to the pump and filter. You should be able to see in there with a flashlight (even better if you have a boroscope cam with decent resolution and lights on it), draw the tank down so you are exposing the fuel pump and filter, stopping periodically to turn the key on and see if you see any fuel spraying out of places it shouldn't.
If you have fuel, stick the plugs back in their leads and ground both back to the engine. You can have a helper hold one against the cylinder, or you can use leads with alligator clips. Press the starter and see if there's a spark across the plug gap. If there's no spark, you'll need to check and see if you've got power to the coils and ignition units. If you have power to coils and igniters and no spark, then the ECU isn't telling the coils to fire. Crank Position Sensor (CPS) is a likely culprit, especially if neither plug is firing. Check wiring to it, make sure nothing is pinched or broken. You could try gently reseating the ECU as well, just to make sure all pins have good contact.
