I am suffering exactly the same problem. Besides the Octave green light blinking, there is another green light between the envelope Release control and the Pattern selector knob that blinks exactly with every click. The volume of this click is unrelated to the Master Volume knob, and there is no way of producing any other sound.
The keyboard has only been used a couple of times, is protected with a special case, and it worked properly until now. Any clue?
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Just edited, as I tried again the next day, finding out that it worked again without problems... Does it mean that I might expect the green light blinking behavior from time to time? Should I interpret this as a warning signal that it will eventually stop working at all?