I have two remote key fobs for my 2010 Cobalt LT coupe. One fob has been mostly used, the other but rarely used. Car mileage about 25,000 miles. Suddenly both fobs don't do anything. For the most used fob I replaced the outer case including the contact sheet. For both fobs I replaced the batteries. Neither fob showed any cracks on the soldered contact points. Still no responce using either fob. I also tried the reset sequence of pressing and holding "open door" button while turning ignition key on and off twice (See http://www.ehow.com/how_7539696_fix-general-motors-key-fob.html) Still nothing. Any suggestions will be much appreciated.