Is it possible for you to record it cranking and upload it for me to hear? The idea that only the alternator was replaced and now it won't crank properly is really odd.
Other than cranking slowly, does it sound normal?
Take a look through this link. It describes the most common causes of a crank no start condition.
Let me know. Also, let me know if you have other questions.
Take care and God Bless,
Sunday, February 14th, 2021 AT 5:18 PM