When in doubt, hit reset to factory settings
With anything
Not surprised the techs sales ppl didnt suggest doing so.. need the sale?
As seems you are not too familiar with the lowrance, I suggest that you note how to adjust the brightness .. write it down.
One day/ well night, you will be cruising home, turn the brightness right down so doesnt reflect on the wind screen...
And you will be very surprised how far down you will have turned it down the next time you turn it on in the day light.
It will appears as the screen hasnt even turned on....
And not having a good reference from pressing the on button, boot up, time and what where to press to bring brightness back up
I mention this because
1/we often came home in the dark
2/ The 1st time happened thought unit had died, eventually after lot stress accidentally hit the brightness.
3/Did not make a note of what to hit when.. And next time again lot time stress...thinking I knew
4/ Every now and again the subject turns up in the forums.