This is a fairly trivial problem. I recently bought a 2012 Civic LX (5 sp auto) to go with my 1992 DX (5 sp manual). The seller dealer gave us keys, the 1st had working radio remote lock/unlock. When we went back later they gave us a 2nd key whose remote did not work. We managed to disassemble the key with a lot of unscrewing and prying and found its battery was completely dead. I got a new battery of the same type (CR1616) but I can't get the new battery to go under the 3 little tabs that are apparently designed to hold it. So I can still use the 2nd key without remote lock/unlock, but does anyone have any hints?