That light comes on briefly just after the flash of the aborted mains reconnection. The shadows it casts on the plant pots seem to match the shadows present when the lights are on before the power cut, though it's very much dimmer.
I infer it's one of the existing lights, which receives just enough energy into its power supply from the attempt to reinstate the mains that the energy discharges as a low intensity glow from the light.
The OP showed us a picture of an LED light fitting under the eaves of his house, pointing directly down so far as I could see, out of shot to the left from the camera's viewpoint. That seems to be the perfect candidate.