Toyota Repair: Multi-information display, toyota prius, c button

Question
I have a Toyota Prius 2006. The multi function display is not working properly. When in the climate mode, The low and High button and the a/c button are the only buttons that will work. I can adjust the temp on the steering wheel and the defrost modes. It seems that all the other screens work fine. Also, when I try and push other buttons on the climate display, it will switch to the GPS screen.
My son attached an external GPS device to the display screen instead of the windshield. This created some small fine scratches. Is this the problem or is there something else wrong with the display?

Is there a fix to this problem or does it require getting a new display?

Answer
The device that's attached to the screen may be causing an inteference frequency so the first thing I would do is to move it away from the display, if that doesn't help the display will most likely need to be replaced which is a kind of common problem, the Toyota dealers have an exchange program for these at a reasonable cost.