Try one more thing before you write it off: turn off all power to the unit by shutting off the batteries. On occasion, our E-80 will not shut down properly (seems to take the right "timing" on holding the off button), and I either get the white screen, or the screen goes black, but you can still see a faint glow of light around the rheostat button. It takes removing all power from the unit to get it to shut down properly and then it starts up fine.
Good luck. I know there are plenty of newer, fancier, sleeker models out there, but I really like my Raymarine.
Best wishes,
Jim B.