"key" light went on

kenchan

if it's the steering lock you'd know for sure as you wont hear the wind-up noise any more when you push the start button...or when you open the door after shutting off your car.

if you dont suspect it's the steering lock, i would first check if the fob battery is low. think it's a CR2023 or something (ck the manual before purchase) available at radioshack or amazon. these fobs transmit rf all the time so it wont last like regual keyfobs for cars without keyless entry/start.

if you had the center console removed recently, i'd check if the plug going to the RF antenna was correctly plugged in or not. ive found this to be a curprit too in the past.

and finally the battery. coming up 4yrs you may want to check the water level inside the battery. wear goggles and gloves, remove the caps on the top and take a peek inside. you should see water barely touch the plastic indicator inside. if not, add distilled water and afterwards, charge it using a wall charger or battery tender/manager.

these batteries will last a long time if maintained. my G's 8yrs old and still on original battery.