door lock motor has died. also I would make the suggestion that you pull the OE (dealer fitted ) alarm out before it strands you. if the remote keys die you are stuffed.
they are $200USD for the motor and catch assembly. its a major pain to get out. one thing I did note was the G35 used a different system the the V35 in regard to remote entry. the G35 appeared to have a separate remote where the V35 is built into the key.
food for thought.