It appears that my 2002 XC70 has a dead battery and the key won't unlock the driver's side door. How do I open it up to replace the battery?

 

Did the key open it before the battey died?
The battery will have nothing to do with the key.
But you might have to get someone to unlock it with the special tools like a locksmith.
I would try spraying something in the key hole and try it again.

 

Tech is correct, it should open with the key. Our battery died unexpectedly recently and I was able to open the dorr manually with the key.