Okay so I bought two new Energizer Li coin cells from Target $5.99. Installed them into the key fob and nothing. So I decided to do the old disconnect the battery for 10mins. Well for whatever reason the alarm started barking about 30 seconds into disconnecting the batt. Hooked the batt back up key in ignition to get the alarm off. Reset the BAS/ESP and voila the key fob started working, both of them. So that's my experience if it happens again I will go for the battery. May order one just to be safe given the age of it.