Looks like this is how you break into the 510;

http://www.agoraquest.com/viewtopic.php?topic=2929 1&forum=50

Service mode access for this model is as follows:
Connect to the TV using the Video Out 2 socket
Hold power key until the WELCOME message appears
Hold down REC, REC STOP, REC PAUSE for about 10 secs until the service screen appears. There will be an "S" in the player's display.

You get a Menu item 9- Hard Drive then 4- Format which I have not tried by assume will format a new Drive

Looks like it will only access 80GB of HD though.

If you can figure a way around this I'd love to know!!!