840D sl, after a restart, the 7 segments is flashing 3-3-4-6. and all leds lits orange.

What happens or changes when you remove the FAN/BATT module or even when the CF-CARD is not inserted? If nothing changes with the status leds and the generated code on its display, than properly the BOOT section/sector is defect (firmware). Communication with the NCU is not possible in any way, also the USB port will not work either and you can better replace the NCU buy a new one. 

If someone else has found an explanation or another solution instead of replacing the module, please let me know.

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Split from 840D SL, 7 segment flashing 3-3-4-6 .