make sure you have you radio code at hand, then you need to check all the fuses in the glovebox behind the fuse cover,and if all the fuses are ok ( pull the fuses out and check one by one so you know where to put the fuse back in its correct place), then inside the engine bay on the n/s next to the battery there is a cover that covers the upc unit ,remove the cover ,know sometimes you need to remove the battery ,remove the cover ,next remove the 13mm bolt ,and disconnect the white connector,then in turn remove and disconnect each connector t untill they are all removed then remove the upc unit and check for green terminals or water ingress if ok same again check all the fuses see how you go .
mark
April 2008