Topic: 788 CI HD DI Not working (Clutter on 2D, Down Imaging totally Blank)

[AriGoldschneider]

So I tested out my new (to me) 788 CI HD DI that was sent to my by Humminbird which replaced a broken unit and this one boots up but the sounder was not working properly. Here are the symptoms:

(1) No down imaging - the screen is entirely black and does not mark any structure or bottom
(2) Static/clutter on sounder - the entire day all I saw on the screen were dots of static and bottom. No fish, no bait, no structure, nothing else. I did not have this problem on my previous 788 CI HD DI unit.
(3) Switchfire Max mode was more clear than Clear mode - when I made the change from Max to Clear mode, there was actually MORE static on the screen. This didn't intuitively make sense to me.
(4) Sonar image was extremely grainy (more so than my previous unit).
(5) Erratic depth readings when at speed greater than 10MPH - this was never a problem on the previous unit.

Could this be a software issue or compatibility with the older sounder? I have a call into Humminbird support but figured I would see if anyone had any thoughts.