Cautions in Removing Battery Terminal and AV Control Unit (Models with AV Control Unit)
WARNING: This page is about a different car, the 2012 Infiniti QX56. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION:
Remove battery terminal and AV control unit after a lapse of 30 seconds or more after turning the ignition switch OFF.
NOTE:
After the ignition switch is turned OFF, the AV control unit continues operating for approximately 30 seconds. Therefore, data corruption may occur if battery voltage is cut off within 30 seconds.