My key stopped working so I took it to the dealership to get the battery replaced, they did this still doesn't work. I then tested my spare key which also no longer works. Both keys will unlock the doors every so often, but it's completely sporadic. I'm taking the car in next weekend, what do you guys think this is?

 

When was the last time you open the car with key? If the key is not use for 7 days (I believe that is the time frame, you can double check the manual). They go into low power mode. you need to open the car using the keyhole and them it come back on.

 

You didn't check to see if the key works after the battery was replaced at the dealer? You should ask the dealer why it's not working.

 

I drove my BMW to the dealership with the Porsche key. I told them about the problems the dealership had no idea and made me an appointment for saturday, just wondering if anyone has had a similar issue.