Flashwizard does not support nfi files so i dont think you can use it on a 600.
You can flash the 600 over your browser though
Follow this guide credits to author.
Flashing a DM600 - Thanks to Macker
Slightly different to other dreamboxes. You can either use the Dreamup software (takes ages) or use the method below instead.
Basically, with DM600 connected to network (no null modem required), you can reflash image, to start first download and install Dreambox Control Centre to PC and have your new image ready and unzipped...
1. Boot your DM600, goto the communication menu and note the ip address.
***note: this is the original IP of the box....192.168.0.5 or similar***
2. Run DCC, connect to the dreambox. Once the network is connected ok, click on the the 'Telnet' option.
3. In the telnet window, type the following, pressing <return> at the end of each line.
mount /boot -o remount,rw
rm /boot/*
reboot
4. You should now get a message saying that the Dreambox is rebooting.
5. Wait a few seconds and then run Explorer (Firefox or whatever) and enter the ip address of the Dreambox in the address bar.
6. On the screen that appears, choose the 'Upgrade firmware' option, find the .nfi file and click the 'Flash' button.
7. Once the progress bar reaches 100%, reboot the box
Note: The IP address is critical. I changed my box IP to my own networks, noted it and then attempted to follow this install.....did'nt work!!!!.....luckily I remembered earlier IP number before I edited it...then worked ok?
I