Following a power cut, I fired everything back up, and generally it all seems OK… all shares / data are accessible.
However, the green LED is blinking much faster than it used to. I’ve noticed it before that event blinking at a slower rate, when the drive was being accessed. Now it just blinks at a rate of around 100 per minute.
I ran the full diagnostic test; it lasted for hours, but passed in the end, with no change to the blinking LED.