Navigation screen not working?

The fact that both units don't have the screen tells us the screen might not be the problem. I would test the fuse #11 and fuse #13 in the fuse panel on the passenger's side behind the kick panel. here is a guide to help and I have included the navigation wiring diagrams so you can see how the system works:

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

Here is the fuse location as well. Check out the images (below). Please let us know what happens.

Hi Ken,

I guess it would have helped if I told you that the first screen was punched by the guy that owned it, and the one that I put in every once in a while, it comes on for a second then goes off again. Nothing is loose and everything is plugged in the right place. I hope I have given you all the info that would be helpful.
Thank you, Kristine

Okay, it sounds like you a bad replacement Navigation unit. What happens is the display driver overheats and goes out, which is common. Here are the instructions on how to change the nav unit out. Check out the images below. Let us know if you need anything else, please.

I just changed it, but it's the one I just described. What I want to know is can I just replace the screen?

Yes, you may be able to, but just to let you know that might not be the problem. This will be more of an internal electronics problem. I would send the unit into a radio repair shop so they can test it or get a used one off of Ebay. I got a used one for my neighbor for $80.00. worked great.

I got a used one at a savage auto part site online, but it was the whole unit CD player, radio, etc. It only displays for less than 60 seconds, if at all. I paid $160.00, but the company refunded my money as they gave a full warranty. Those units are hard to find, but I will keep looking. Thanks for your help.

This will be your best bet, finding the screens can be very difficult because the manufacturer will use a screen from another company which is not known by anybody but the manufacturer.