my key remote for my 02 maxima doesn't work anymore so I've seen some on craigslist, so what happens if i buy one like how do i program it

 

I'd try replacing the battery first.

 

When mine broke I bought one off amazon. Looks and feels just like the OEM one and works great. Just a little under 10 bucks with free DIY instructions. Its easy and only takes minutes

 

-Close and lock all doors
-Put key in ignition 6-10 times within 15 secs
-When hazard lights blink twice (program mode)
-Turn key to acc mode (furthest without starting engine)
-Press lock/unlock on fob
-If it worked you will get response right away.

Thats what I remember right off the top of my head. Think thats it though. Ive done it a couple times on my 4th gen and now my 5.5 gen. Good luck

 

You should try replacing the battery first. If all the components inside look good, you could always just buy a $4 replacement shell/case. I just got one off of ebay for about that much and just transferred over the internal parts.