When the battery begins to run out on the key fob, it is best to change it sooner rather than later. Otherwise you will have to manually unlock the boot and reach into the car to open the door handles. Really not cool!
All G2 fortwos use a single battery, some older fortwos use two batteries. When the battery begins to fail, the car indicators will flash 9 times upon locking.
Note: If you car starts to flash 9 times, you only have 100 more presses before the car will lock you out!
Remove the key from the keyring.
Using a key or a coin, lever the casing apart as shown below.
The battery is located directly on the PCB. You can't miss it!
Remove the battery and replace with another Lithium CR 1225 cell.
Note: Fit the new battery within 1 minute of removing the old one.
Fit the PCB back in the front section ensuring that all three pegs are correctly located.
Close up the casing and test.