I can think of two possibilities;
1) your CDR might be bust. Try burning a new one yourself. The files are available at
www.geocities.com/denondvd
You need to burn the file bank30.rom onto a disk and it should then in theory autorun the update when you insert it into your player.
OR
2) the newer firmware no longer looks for bank30.rom on disks for upgrade and searches for another file? Bad news if this is the case, and will despairately need a new version of the hacked firmware.
Where did you buy your player? Have they been helpful at all?
If you do find a newer version of the hacked firmware I would be very interested to see it.
Regards,
Ian Guinan