2
@CAJack42 highlighted a potential problem for older model year Passport owners due to a weak key fob battery (such as, keyless entry not working well). Key fob battery life is approximately 2 years, dependent on usage...
If your key fob battery is completely dead, this is the emergency procedure for starting your vehicle...
The replacement battery is CR2032. Put an extra battery in your glovebox or center console if you may need to replace soon. Here is the procedure for key fob battery replacement...