Nikon D6 Reference Manual page 258

D
Burst Photography
•
Depending on shooting conditions and memory card performance, the
memory card access lamp may light for anywhere from a few tens of
seconds to around a minute. Do not remove the memory card while the
memory card access lamp is lit. Not only could any unrecorded images
be lost, but the camera or memory card could be damaged.
•
If the camera is switched off while the memory card access lamp is lit, it
will not power off until all images in the buffer have been recorded.
•
If the battery is exhausted while images remain in the buffer, the shutter
release will be disabled and the images transferred to the memory card.
206
Choosing the Operation Performed When the Shutter Is Released (Release Mode)