Okay so I bought the car from the dealership 4 days ago and the navigation system asked for the 4 digit code. I enter the code and it goes through the whole reboot system and the navigation map shows up, but when I turn the car back on it ask for the code again. Can anyone help me out?

 

That means that the battery power is disconnecting for some reason.
Tighten and clean the battery clamps as necessary. Check the battery cables for corrosion as well(including under the sheathing); replace if necessary. Check cable tightness at the ground and starter ends.
Then check battery voltage/condition- a dying battery can cause the Navi and/or radio to ask for a code.

Report back if that doesn't resolve the problem or if the car has other electrical issues.