Hi - I just got back from a long trip and can't open the door. I changed the keyfob batteries and still nothing. Is the battery dead? Fixable?

 

sounds like a dead 12v battery. Happened to me after leaving it at the airport for a week. Later discovered I had left an overhead light on. Did you try opening the door with the mechanical key inside the key fob? Then you can see if the car has any power.

 

This is probably too late to be of use to OP but would connecting a jumpstart battery to the terminals under the hood help?
I mean if the 12v battery fails, the car can still be jump-started right? Then wouldn't same battery help to pop open the door?

Edit: oops, just realized the hood isn't openable either :-)