I have a 2004 Chevy impala and I’m having the same issue. I changed the crank shaft sensor and it started right up but when I turn it off it never started back up. Cranks over but it does start. I was thinking it might be the security system. Because the radio was replaced
Please don't "hijack" someone else's topic even if it sounds similar to yours, post one of your own. Thank you. (Topic split.)
Follow the steps in the FAQ for diagnosing a no-start condition.
To quickly narrow down whether it is a fuel or an ignition problem spray some starting fluid into the throttle body intake, and crank the engine over. If the engine briefly fires up you have spark.
Fuel pump, pump relay are my first thoughts. Then comes the starter, perhaps the immobilizer system.
