I had to leave the 04 out in Arizona heat for several hours and when I got back to it the climate control and stereo were dead, and the display just glowed a dim diffuse red. It didn't get better in the (relative) cool of the garage. Did I cook something permanently?

 

Behind the Head unit LCD Display is a connector that likes to pop out of the female plug. My guess is as the inside of the car got warm it caused that to disconnect just enough to cause this issue.. If you tap the Dash above the Display and you get it to Blink or work then you know that connection is loose.. You will need to pop out the LCD display and remake the connection.. .. Search the Forums here for this as many including me have had this issue.

Good Luck !

 

Well, this is bizarre. Letting the car rest overnight it recovered. I ran some errands and again had to leave it out in the heat. On return the display was blank, and there was no response to A/C controls or radio, but because I had left them on when I parked the compressor kicked in and there was music. As the car cooled down driving home the display gradually got brighter until everything worked fine. It seems like the LED display is not the only problem.