If everything else fails, this is a way to eject a stuck mac mini dvd or cd.
Look at the picture and the orange flex card. It looks like its missing some components, like an eject button and an activity led. If you shorten the eject button with a piece of wire or similar, when the mac mini is powered on, the disc will eject.
(And if this fails, open up the dvd/cd by removing the top cover and gently remove the disc.)

The eject button is the 4 soldering points at the leftmost position.
Oh, and you need to open it first :-) Maybe it is possible to eject with it unopened, haven't tried it yet. If so, please mail me.