Canon EOS 7D Instruction Manual page 244

Troubleshooting Guide
The access lamp still blinks even when the power switch is set to <2>.
If the power is cut off while an image is being recorded to the card, the
access lamp will still continue to light/blink for a few seconds. When
the image recording is completed, the power will turn off automatically.
The battery becomes exhausted quickly.
Use a fully-charged battery (p.24).
The battery performance might have degraded. See the [7 Battery
info.] menu to check the battery's performance level (p.230). If the
battery performance is poor, replace the battery pack with a new one.
If you keep displaying the Quick Control screen (p.38) or shooting Live
View shooting or movie shooting (p.131, 149) for a prolonged period,
the number of possible shots will decrease.
The camera turns off by itself.
Auto power off is in effect. If you do not want auto power off to take
effect, set [5 Auto power off] to [Off].
Shooting-Related Problems
No images can be shot or recorded.
The card is not properly inserted (p.29).
If the card is full, replace the card or delete unnecessary images to
make room (p.29, 179).
If you try to focus in One-Shot AF mode while the focus confirmation
light <o> in the viewfinder blinks, a picture cannot be taken. Press the
shutter button halfway again to focus, or focus manually (p.35, 92).
The viewfinder is dark.
Install a recharged battery pack in the camera (p.26).
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