Having pulled the dash and nav screen apart on a few occasions now there are a few areas I have seen that can cause problems.
The center speaker bolts can become loose , the screen wire harness are the likely culprits. Very simple and safe to fix with the right trim removal tool which only costs a few dollars. Just say if you need more info and you are happy to do this yourself. (I have some DIY dash /screen removal PDFs) You can buy the tool from many specialty tools shops. That and some painters tape is all you need What members say about taking to a dealership is spot on. Recently had an annoying rattle in the centre console which the dealer tried to fix then said that the whole centre console needed to be removed to find the rattle. By simply unclipping the handbrake gaiter I found the rattle in a few seconds.Makes sense if you think beyond an hourly rate