Hi Lewis
Yep those pesky CD readers can have a hard bite!
There are other things to try
There is a "reset CD" function in the menus, see below,that is wort a try - try it then press the eject button.
Power off the unit then power on while hold in in the "eject button" may work
Some people have found that attaching an external USB CD reader to the back then powering up sometimes ejects the disk
Alternatively there are some "under the hood" Linux OS commands that may work - there are detailed in other Threads on this forum. You have to SSH into the B2.
Keep trying
Fred