The wires are clean and doesn't seem corrupted..I don't have anything at hand to check if there is any current inside.
Are you sure that in the fuse box in front of the battery there are not any fuses that can be damaged ? The draw on the box seemed as a description of fuses : it seemed a lot like the draw on the fuses box inside the car : a description of the fuses circuit and an amperage 5A, 10A etc...In the Haynes Service and Repair manual for Micra k11 manual is the description of a fusebox under the hood also..But they didn't imagine they had to put a description how to open it also :
"Additional fuses and circuit brakers are located in an auxiliary fusebox in the engine compartment, attached to a bracket on the left hand body panel next to the battery.Fusible links are located in a further fusebox in front of the battery".
I'll take a photo of the box this as soon as i can.
What bothers me is that I couldn't found the exact fuse which relates to the rear plate number light
Thanks a lot for your help and sorry for my english...I'm french
"Open the bonnet (hood) and locate the battery. In front of the battery there is a small fuse box. Open this, and locate the two 15A fuses. These run the lights, one for each side (dip and beam). Now, someone at Nissan obviously designed this at 5:29 on a Friday, because the cables that enter this fuse box are VERY taut. "
those are the headlight fuses bog, the fuse you need will no doubt be linked to the rear lights, you,re best to check for live on the wire in the tailgate, and travel back along that wire if its dead