Ok so my navi system just stopped working. At first it would tell me it's rebooting or something like that and to not turn off the vehicle. Now it's completely gone. It says external system not connected. If I download the latest version of the navi map will it come back on. Please help. And warranty is gone just as FYI.

 

Try doing a hard reset on the navi by disconnecting the battery. If not, maybe you can open the console and check if there is anything loose:
https://www.clublexus.com/forums/is-...n-fix-diy.html