Canon EOS 70DN Basic Instruction Manual page 592

Troubleshooting Guide
The LCD monitor does not display a clear image.
If the LCD monitor is dirty, use a soft cloth to clean it.
In low or high temperatures, the LCD monitor display may seem slow
or may look black. It will return to normal at room temperature.
[Eye-Fi settings] does not appear.
[Eye-Fi settings] will appear only when an Eye-Fi card is inserted in
the camera. If the Eye-Fi card has a write-protect switch set to the
LOCK position, you will not be able to check the card's connection
status or disable Eye-Fi transmission (p.401).
Playback Problems
Part of the image blinks in black.
[33: Highlight alert] is set to [Enable] (p.294).
A red box is displayed on the image.
[33: AF point disp.] is set to [Enable] (p.294).
The image cannot be erased.
If the image is protected, it cannot be erased (p.320).
The movie cannot be played back.
Movies edited with a computer using the provided ImageBrowser EX
(p.456) or other software cannot be played back with the camera.
However, video snapshot a bums edited with EOS Video Snapshot
Task (p.286) can be played on the camera.
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