Replaced alternator and no start with key

Welcome to 2CarPros.

Have you checked the starter fuse as well as the starter relay? They are both located in the under hood fuse / relay box. I attached a picture below showing which ones to check.

Here are a few links you may find helpful:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

https://www.2carpros.com/articles/how-a-car-fuse-works

https://www.2carpros.com/articles/how-to-check-a-car-fuse

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

https://www.2carpros.com/articles/how-to-use-a-voltmeter

https://www.2carpros.com/articles/how-to-check-wiring

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Let me know what you find.

Joe