Sounds like the mk4 has crashed because there was an error in the firmware update disc. If I didn’t know better Id say that you have a mk3 as this is the classic symptoms of a wrong mode disc.
Did you get the image from here, if not get it now.
http://www.megaupload.com/?d=O8YINIDZ
Unzip and then burn at the slowest speed available for the disc (or x1 speed) check the disc for errors, the follow the update procedure.
When its finished writing your new firmware cd,
Goto the car open the drivers door,
Goto the nav computer and press eject on drive,
Eject the map disc,
Switch ign to pos 1, leave door open.
Insert firmware disc into drive, follow instruction on nav screen.
Wait (approx 6 mins) till sat nav asks to eject cd and reboot.
Eject cd,
Confirm reboot.
Thats it.
Do not swich off ignition or close the door when doing the upgrade.
P.S. Welcome to the forum.