navigation and radio - on/off button on several time but nothing illuminates?

Hello,

It could be caused by a burnt fuse. That should be the first item that you should check.

There is a fuse block located behind the passenger seat.
Check these fuses:
#59 - 5A
#66 - 25A
#77 - 20A

https://www.2carpros.com/articles/how-to-check-a-car-fuse

If the fuses are good the it could be a faulty module for the radio unit. This vehicle has a control unit for the radio/navigation. That unit could have burnt circuit board that triggering the issue you are having.

Please let me know of any questions.

Thank you.