Hello, hopefully a simple one but I have done a lot of searching and come up blank. Son's '08 1 litre Aygo's rear windscreen doesn't seem to work at all. Fuse is fine, I have put a multimeter to the metal connecters across the window and getting no voltage, which suggests no power getting to it at all? Switch seems to have been replaced as the light doesn't fit nicely in the switch light's hole, but it does light up when pressed. Looking on a YouTube video and an eBay advert