You can test the unit with only the power cord attached to a known good 12v source ... (use a 3amp fuse in the red positive wire) ..
*Press the power button ...
*Press the "Menu" button when you see the HB logo appear ...
*Use the 4way cursor to choose "Simulator" from the 3 choices in the popup box ...
*Use the 4way cursor to the right to initiate Simulator ...
*Simulator allows access to all the functions of the unit just as if it were in use on the water ...
*You can cycle thru the views by pressing the "Views" button ...
*You can press "Menu" 1 time to open Xpress menus for the view being displayed ...
*You can press "Menu" 2 times to get into the Main Menu System ...
Check the rear of the cabinet where the cables attach to look for damaged cable sockets ...
Here is the manual for the 900 series units ...
http://www.humminbird.com/WorkArea/D...t.aspx?id=3146
And you can always bring your questions here ...
Rickie