Much easier to just buy another key (even just to unlock the doors and not start the car) and stash it somewhere accessable...... I know of some that stash it behind the rear license plate....and others that wire it inside the front lower grills.
I had the same problem, I had disconnected the battery for a long term storage (5 weeks) and must have armed the security controls. By adding 12v. to the C3 terminal and following the listed fixes, I was able to open the front hood.
Thanks to all!