My car wont start, I have a new battery in it and I have checked all the fuses. on 2002 Infiniti I35

I tried to crank it and it doesnt sound like it is trying to crank up. I put my carMD on it a couple weeks ago and got the code 1800, so I replaced the Variable Intake Air System solenoid valve, and also got a new battery. All my light on my dash come on, but even after 3-6 tries it still wont turn over. What could it be? Any suggestions would be helpful. Some have told me it could be the starter, a sensor, or even as small as a fuse.

Asked by for the 2002 Infiniti I35
Clarify? Crank-no start or no-crank , no-start. Cranking= engine actually spinning , 'turning over' is often misinterpereted. When you say "it still won't turn over" do you mean you don't hear any sign of firing/trying to run?
I got it started eventually, and was able to take it to my mechanic and they told me that after testing it, that it is my Alternator. Going to cost me about $400
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it sounds like a starter to me but to be sure have someone try to start it then check for power on small wire going to starter solenoid