Cranking is starter action, will it crank? If it cranks good but won't start, have a helper crank it while you visually check for spark at the spark plugs. If it has spark everywhere, use a gage and check fuel pressure.
If it won't crank at all, then use a digital multimeter, make sure battery has a full charge. Check for voltage at the starter. Any testing at the starter, make sure the tranny is in park or neutral and the parking brake is set.
I haven't looked at your security system, yet, just a thought.