Tips to eject CD:
1. hold down the eject button and wait while you hear the cd trying to read (I think I heard it do this about 4 times) keep your finger on the eject button the whole time and once you hear the nav unit stop trying to read the disk (about 1.5 - 2 min) let go of the eject button and press it again quickly and the disk pops out.
or 2. Remove power from the nav drive (pull fuses, disconnect battery, or remove connectors from back of nav drive - your choice) and then reapply power while holding down the eject button on the nav drive
http://www.xoutpost.com/navigation-sy...stuck-mk3.html
http://www.xoutpost.com/navigation-sy...-mkiv-dvd.html
Yes, go ahead and run a Nav OS update again. Try your V27 disk.