I’m sure Rickie will get on here with way more knowledge than I have, but my first reaction is you are not getting proper voltage to that unit. Is it wired directly to battery? If not where is it wired to? I would first and foremost save everything you can to SD cards and load to Humminbird PC for safe keeping. Then I’d replace cranking battery with biggest battery you can fit in the space you have. Then I would start at unit and trace wiring back to battery checking every thing for a bad or weak connection. You really should have everything wired directly to battery. In your case with so many things I’d suggest a fuesable buss bar with 8 gauge wire from battery to it, then wire each unit to that bussbar with the appropriate fuse.
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Charlie Weaver USN/ENC 1965-1979