I was hoping someone would respond with the cause so I could cause mine to be off. I hate having a bright screen in my face at night so every day I have to manually cycle thru the menu to turn it off.
Is there an actual power button on yours, or are you just pushing a control button?
All I can think of for now is maybe resetting the car by disconnecting the battery and let it sit for a bit to ensure any caps are drained. Just a stab in the dark but it's what I'd do. I imagine you'll lose all your radio presets and possibly all other settings, and I assume it'll ask for the radio code too, if they still do that.
What about turning the ign on but not starting? If you get a screen there then it's a clue. Like maybe if voltage drops too much during start and the sys thinks it'll save power by not turning that on?