I had the same problem but now it has packed up altogether.
I could hear the motors going attempting to open the tray but it wouldn't. Sometimes I found tapping gently on the front of the tray seemed to help. Othertimes just keep pressng the button on the remote seemed to work but not on the open tray button on the unit itself - that didn't.
This model has been fairly problematic from the start and it has only lasted 30 months.
Ian Pedder
January 2008