2004 galant 4 cylinder wont start

I had been driving it. Thought I noticed a screeching sound and planned to ask my father about a belt problem. Fair warning: I'm no mechanic or car guy by any means. But he's fairly good at troubleshooting, etc.
I was backing out a parking space and the car just died. It tries to crank but it doesn't ever actually start. My brother and father both assumed it was the fuel pump, because they couldn't hear it, so it was replaced. Still nothing. My dad then replaced the crank sensor and still nothing. He said he's stumped and isn't sure what else it could be.

Any help?

If it's just cranking without any backfire, it's most likely the ECU.