It took some time time to find it, but here goes
http://www.vcdhelp.com/dvdplayershack.php?select=Grundig%20GDV%20620HT&get=Get -- 1 ------------------------------
"open the drive tray
type 9 8 1 7 on the remote keypad
you will then be into a hidden menu
choose regions 1-6 or 9 for region free using the ENT button. You can also switch MacroVision at the same time."
-- 2 ------------------------------
"The GDV620 is one of the easiest hacks around.
1.Power on,and open drawer.
2.Key in 3838 with handset.
3.A menu will appear,"Region Code",and "Macro On/Off".
4.Region code can be set by pressing Enter key repeatedly to get desired region,and Macro,on the line below,can be accessed with the "down" button to be turned off if you wish to tape any DVD's.
5.Press Open/Close button to store.
As yet, I dont know if there is any limit to the number of times it can be changed!!"
-- 3 ------------------------------
"to hack to the Grundig GDV620HT (bought in Dixons or Currys in Uk Or Ireland)
1)open disc tray
2)on the remote control key in 9817
3)a menu now presents. THe region will be set to "2" and macrovision will be on. Set the Region to 9 to enable all region disks, and disable macrovision"
Just quotes, I don't know if they work, no guarantees.
Thomas