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The failure pattern, plus the rhythmical clicking all the time, means (as I see it) that either the control circuitry has malfunctioned (thus the opening and closing), or else the door position sensor (or similar) has failed... but if it were only the sensor, then the door would not fail to open and close altogether now.... so the other alternative is the motor has failed, perhaps owing to the constant opening and closing.
At any rate, I don't think there is much you can do, except take it to a repair shop for Bang & Olufsen devices of this sort, in your region.
If the Beosound device is within 1 year of its purchase date, then it will be fixed by B&O and you ought to be charged nothing, I think, for the repair.
If you will tell me where you are located - by zip code, or by town/city and state/region - then I will look up contact information for B&O-repairing shops in your region.