My mom has a 1993 Nissan Altima XE/GXE/SE/GLE, the milage I'm am not sure of, engine size is a 2.4L DOHC. The problem she is haveing with her car is that the passenger side door won't open. What happened was the door got locked and when I tried to get out it would not unlock. We tried unlocking it from the outside but it still wouldn't unlock. And when we pressed the unlock button it would make a sound like you were playing with a spring. What should I do and Is it something that I could fix at home?