LED Light fitting has started making clicking sounds after power outage
I think it's the motion sensor, which this light is equipped with.  

The motion sensor is probably not bespoke for this light, and is a commodity module.  The module supplier doesn't know if it will be controlling 0.05 amps or 5, so it uses a nice burly mechanical relay that is probably overkill for this light.  That's what you are hearing.  

I also suspect the motion sensor may be designed for low voltage, which makes current proportionately larger (quite much larger for 12V). Current decides the relay size.