2006 e350 19k
battery in trunk no power, used the long metal key in key fob, side
the release end of key fob, pull out and push in and turn and pull
the trunk open, replace the main battery under trunk mat. No 2
battery is in engine right side rear under a/c filter, no reset radio
code install a 8 year 3 year free replacement new battery
the 2001 e320 have a back up long metal key in the key fob also same, battery is under rear seat have to reset radio code