Need help!
 

Hey guys! So I changed the battery, alternator and cleaned the ground wires by the differential, and engine. And it still doesn't start, what could it be? Could it be because of the refurbished alternator I bought from autozone and it has gone bad already? So here's how it happened. I went cruising with my friends and I was shifting about 4000RPM, when I came home, I tried to start it. It sounded like the car had a hard time starting. (1990 1.6l Miata)