Speaking of dead key fob batteries, I ran across this in the service manual:

The batteries in the Remote Keyless Entry transmitter can be tested by pressing and holding both the lock and unlock buttons simultaneously for more than one second. The batteries are charged sufficiently if the LED next to the ignition key blade lights up briefly.

A built-in battery checker. How cool is that? You can also change the way the car unlocks the doors when you press the button. Read on...

Global/Selective Central Locking

The keyless entry system has a Global or Selective mode function for central locking that can be programmed by the customer. The factory setting is Global, which will lock and unlock both doors, rear liftgate and fuel door centrally when the respective button is pressed once. The Selective mode will only change which power locks unlock. To activate the Selective mode, press both the Unlock and Lock buttons simultaneously for approximately five seconds until the battery check lamp in the transmitter flashes twice. The Unlock button will then only unlock the driver door and the fuel door when it is pressed once. Pressing the Unlock button a second time, unlocks the passenger’s door and the rear liftgate. The factory setting can be restored by pressing both the Unlock and Lock buttons simultaneously again for approximately five seconds until the battery check lamp in the transmitter flashes twice. If the vehicle was locked using the power lock switch in the center console while in the Selective mode, opening a door from inside unlocks that door only. If the vehicle was locked using the power lock switch in the center console while in the Global mode, opening a door from the inside unlocks both doors and the rear liftgate. If the vehicle was locked using the RKE transmitter, the doors and rear liftgate cannot be unlocked using the power lock switch in the center console. If the vehicle was locked from the outside, opening a door from the inside will not unlock other openings but it will trigger the alarm.