As above, swapped over my father-in-law's amundsen for a columbus unit, only to be told 3 weeks later that he thinks he has left a CD in there that he had borrowed from a friend. Is there any way to get it turned on/eject the cd without fitting it back up to the car??

I would be tempted to put it back in the car. Whilst probably it could be done by connecting 12v across the positive and negative pins and pressing eject, I would be worried the unit is geared up to a CANBUS type signal for the code etc which might cause issues.

You should be able to power it up on a bench. When we did this, it needed power to two pins rather than one though, the second is possibly for the antitheft circuit?

 

It should then power up and ask for a code, at this point you might be able to eject the CD without needing to enter a code. Once back in the car it should work as normal once again.

 

Otherwise, it's a pretty quick job to connect it to the car temporarily just to get the disc out.