Help me troubleshoot my Clarion M255 CD receiver. The display is illuminated but nothing happens?

I have a Marine Clarion M255 head unit in my car. I didn't install it myself. One day, I put a CD in and it stopped playing after two songs. The display stayed lit up (but with no words or messages on it) and is still lit up to this day if I attach the head unit. The CD is stuck in there. What could be wrong and how might I fix it?