Hi kwakisaki,
Thanks for your comments. Before get it back running again I got only one error with the Check sum which could the reset in the settings.
You can solve "Check sum error" follow next steps.
AUX 0803 (Menu -> System -> Sum Check Error Reset)
Check box move to Off.
and Press "ESC" button twice on T/P.
your E0903 error message will be clear.
but, When a Cold start (Turn off -> Turn On) system, that parameter will be automatically returning to On.