Sorry to be the bearer of bad news, but your 360 is now officially an expensive doorstop. If you didnt retrieve the key prior to erasing there is no way you can recover the key. So now, the Xbox will ONLY be able to play movies.
To eject it, you have to remove the chassis and use the part on the underside of the drive to release it and eject it. Allthough, it's useless now without the key.
My best advice, would be to try and break the xbox down and sell it for parts, if your in the UK I'll give you £20 for your liteon drive.
The drive has no firmware, so it wont eject or anything like that.
You have to remove the casing from the drive and use the small plastic lever just below the motor, slide that across and the drive lock will undo, then slide it further and the drive will eject about an inch, then you can pull it out the rest. Although this won't do you any good now.