Well, don't know that one, but try to pry it up and keep pressing the eject button same time, use a pair of sharp scissors or some this knife with sharp tip....or if that fails, then take the unit out, then necessary covers/housing off until you get to the tape so you can remove it this way....but search in google your problem and see if it is not something common with a very easy solution.
But thats what I would do.
A3 Bose Concert Stereo 
Linear Mode
