Nissan Sentra 1994 Rearing light/lost of radio volume

Dealer, supposely replaced a newer wire to the air-conditioner[it still does not work at all, now they say it might be a cooler problem]; I don't know if this wiring effected my rearing lights [I did not check as I leave since it was the dealer. However, now I know better. By accident left inside light on and drained the batteries. The next day I replaced with new battery [1st one was the wrong - directions and caused a couple of fizzles along the area, stopped immediately] and noticed that my rearing lights were not working plus the radio inside [it lights up] but no volume? Checked the interior fuses and fuses along the battery, replaced a few that happened to have been burned out. Yet , still the rearing lights do not turn on when I place into it. Is it a fuse somewhere [hard to reach] or is it due to a wiring burn-out? Or/And is it due to the airconditioner wiring? and desperate I suspect your rearing lights are what we Yanks refer to as the back-up lights. When these lights fail, the fault is often the back-up light switch mounted in the transmission housing. This is usually simple to replace. As for the radio problem, it might have been permanently damaged when you reversed the battery. These two problems are not related to the A/C problem.Car Repair Talk's forum.