2013 Fiesta Hatch SE 5 speed. Key fob has key for starting engine, will also open driver door. I thought the battery was going down as it was reluctant to unlock the doors or hatch. Battery checked out at 3V. Spare key fob unlocks doors, no problems. I am guessing the one I use is wearing out. What is involved with getting a new fob? Easy to get the new key cut?? How to get the electronics to talk to my car.