2000 Jetta fuel cap won't open

We just bought this for our daughter and the alternator needed replacing immediately. Now the fuel cap will not open. We can hear the sound, but it just ain't happening. Everything else seems to be functioning fine. Any ideas?

remove the trunk lining on the passenger side and look to see if the rod broke off or disconnected from the trunk release motor

Thanks, veedub! I will check this out when I return from a trip!