Alright, I just retrieved my voicemail and heard that my car is ready to be picked up.
They briefly mentioned that they had to replace the ECU and then the car was all good. As you recall from my first post, the problem was the signal was not being sent from the ECU to the starter to turn the engine over. I'm still curious to know what they think that would have caused this. It could be a fluke like what Zrider mentioned except mine was permanent, haha.
I'm at work right now so once I get off, I'll have to return the rental to Enterprise and then get a ride to Nissan. I'll ask more questions to hopefully get more info so I can share with all of you. Stay tuned!
Side note, I like the Altima! It would be a daily driver I would consider in the future. I definitely enjoyed it overall more than the Corolla rental I had fairly
recently. The only upside is no matter how you drove the Corolla, that sucker got like 30+ miles a gallon.