How do you replace the key battery on a 2008 Mitsubishi lancer?

Answer 1

Remove the metal key from the smart key receiver.

There is a tab at the top of the smart key that is small, small to get a small screwdriver placed in. Use such a tweaker (jeweler) screwdriver or something equivalent of that size to pry the top half of the key from the bottom half.

The battery is easily visible once prying the key open is complete. It uses a standard 3V battery found at any Radio Shack, Wal-Mart, etc. The exact model number of the battery is imprinted onto it.

Once the battery is replaced, snap the key back together and place the metal key back in the smart key.