Hello and sorry you're having problems.
This is caused by a processor glitch, or a hardware failure within the Bose.
There's not much on a user level you can do to fix this on your own, but here are a couple of things to try.
Disconnect the Bose from power, then remove the umbilical cable between the Changer and the Main Unit. Press and hold the Eject button for 10 seconds and release. Then re-connect the umbilical cable between the two devices.
Then, press and hold the Eject button- while plugging the system back into power. Continue to hold Eject for 15 seconds, or until you hear the Eject motor engage.
Then attempt to play a disc.
If this does not work, then the player is in need of service- more specifically the Eject mechanism in the 3 disc changer has malfunctioned. In this case you would need to contact Bose Service, as they are the only ones that repair their systems:
For assistance with your product, please call us toll-free at 1-***-***-****. For help with our aviation headsets, call 1-***-***-****.
For the best possible service, please have your product nearby when you call. Hours of operation: Monday – Friday: 8:30 AM – 8 PM ET
If you need further assistance let me know. Please do not forget to click the 5 STAR RATING, at the top of the page for my efforts. It is my livelihood and you can follow up at any time if needed.