Welcome to Just Answer!
I have a few tidbits of information for you I found:
a.)"You have gotten the unlock/lock out of sequence with the fuel door open/close. Open the fuel door then unlock the car. close the fuel door and lock the car. Then you should be back in sequence! The fuel door does not have a button or anything to "spring it open" walk up to it and just push it in (make sure your doors are unlocked)"-clubnico
b.) 2003 - 2006 Infiniti G35 Sedan Gas Door Lid Issues
http://www.auto-talk.net/how-to/infiniti-g35-sedan/2003---2006-infiniti-g35-sedan-gas-door-lid-issues.htmlI am sure many of us have gone through this experience where the gas lid appears to be stuck. Many G35 owners have made this a huge issue and have been calling Infiniti for instructions. Solution is very simple.... According to the owner's manual, put the key in the driver's side door and turn it towards the rear. Unlock the doors using the door master unlock switch. Use the keyfob atleast twice after this step. This will override the factory settings or in simple words reset the module.In case this override doesn't do any good, this means the gas door actuator is bad. You can order that from the dealer (actuator part # XXXXX). In the mean time you can reach from inside the trunk and pop open the door.
If you cant manage it by yourself, dont go and scratch you car up prying it open... bring it to the dealer ASAP to get it taken car of prior to you running out of fuel.
-Auto Tech Guy