The Lowrance 5HDI on my buddies boat has recently stopped working. When we power up the unit, the Lowrance logo flashes on the screen and then it goes black. We checked the battery terminals and connections for corrosion and removed any that was present. Rechecked the connection at the display unit and the transducer and they look fine. What could enter problem? Do you think the issue is with the display, transducer, or something else. Thanks in advance for your suggestions.

Matt