Hmmm... If the player have built in Navigation then you can power it on from its Setup.
On the main menu where you can see icons for DVD, Radio, Aux etc, you can see "Setup" on the top right corner. Press setup and you'll see another menu. I think the tab that you have to click is something related to system settings or something like that. I am not sure but you can check every tab option. And yes, it will ask you password. Insert as many "8" as you can and hit OK.
There you will see buttons to switch on/off DVD, BLUETOOTH, GPS etc. If GPS is switched off, switch it on. Maps can be loaded with the help of a memory card.