Common issue is the LCD and instrument s start malfunctioning…Remove the Binnicle and once on the Bench ..remove the rear cover.
In the bottom corner behind the LCD there is a metal connection to the PCB board….make sure this is contacting good.I have marked the contact point..it’s the little protruding piece. This is the Main Earth to the PCB Board.
Refit and hopefully all working
Well this fixed my issue which was similar to yours