There is NO disc in machine - I’ve fused the radio - reset - still no luck - how do I eject a non existent CD?

It’s empty and won’t let me put in another.

Not sure about your radio / cd

but lots of Cd players have a pinhole somewhere near it , on a computer a paper clip straightened out and then inserted in the pinhole while pressing eject normally open draw or pop the CD out etc.

Other option is a good blow with airline on the CD insert bit could be dirt on the sensor etc.

Good luck