My recent old bass boat purchase included a Lowrance Hook 7 fish finder.  Every time I start the unit, it comes up so dark I can barely see it.  I've had to reset the unit back to default settings (no big deal in itself).  But the next time I start it up, it's dark again.

 

Any ideas?

It might be getting into night mode. I had a hook unit that would do that sometimes. On the main option screen where you go to turn it off, there is a night mode option. 

there is a screen under settings that controls the brightness settings if its not on night mode

Oddly, it seemed to work fine today. Oh well.

Push the power button once without holding it down and the brightness menu will appear 

It could also be low battery voltage.

You need to get a manual for your unit, can't see fish and now brightness.

Tom