1. Turn off the N800
2 .Plug in the USB cord and connect the N800 to the Linux box.
3 .Turn on the N800 while holding in the "Home" button until you see the USB icon in the top right corner of the screen of the N800.
4. Download the flasher-3.0 utility from maemo.org to your Linux box.
5. Execute the flasher with the following options: ./flasher-3.0—enable-rd-mode
6. Reboot the device
7. open a terminal and sudo gainroot and set a root password with passwd