I have a 2005 Nissan Altima 2.5 with about 80,000, 4 cly and about 2 weeks ago we left the car running with the air condition and radio running for 2 hours while parked to keep a birthday cake cool since the event was taking place outside (my bright idea). Didn't think this would do any harm but after two hours I turned the car off and when I came back hours later to restart the car, it was dead. Turns out it killed the battery but when we replaced the battery we had no problems with the car cranking up but a couple of the tail lights were out. We got light bulbs for them but by the time we attempted to replace them, they were working again. Well a couple of days later, someone told me that a couple of my lights were out again. Why would they go back and forth. Second, the radio hasn't come back on since this incident. We have never had problems with the radio at all but once the car died, the radio never worked again. Someone suggested that the Nissan has some kind of code that needs to be entered (as a theft prevention) but when I called the dealership I got the car from, they said the Nissan doesn't have that. It is a factory radio and has never been tampered with. Any idea why this would happen when the battery dies and how to get the radio back working?