Car wont turn on

Where did you get voltage for the LOC?  What fuse did you tap?

Describe "won't turn on" in a lot more detail. 

the push button start Altimas are notorious for not starting when voltage is too low. Provided that you wired everything up properly, you may want to start the car and reconnect everything and see if it works then. May not be the best suggestion if youve wired something up wrong. That being said, if youve wired something up wrong, you probably would have had severe failure already since 12.4 volts will blow something up as soon as 14.4 will (the difference between the alt running and providing electricity vs just the battery on a stock charging system).

Id bet dollars to doughnuts that its a voltage issue