04 Suburban Won't Start

Make sure battery has a full charge and connections all good? I looked at info for 04 chevy sub 1500, 5.3 liter engine. note the wiring diagram. Can you pull starter relay from fuse box, if so, that should kill the starter motor? If you pulled one of the fuses at the top, that should have killed the starter motor? Did you replace starter and solenoid as an assembly? When unhooked battery, that might have triggered the security system? Have you done any testing at starter motor concerning voltage and ground? At bottom of diagram, you see top of starter motor, Terminal B comes from battery, hot all the time. Terminal S goes hot when starter relay is energized. Any testing at starter motor, make sure transmission is in park or neutral and parking brake is set. Vehicle can't move. You can use test light for testing. Starter motor grounds through engine block. Hope my post makes sense, sometimes, I get to rambling. good luck