Samsung QA65Q70TAWXXY E-Manual page 183

HDMI IN
HDMI IN HDMI IN
First disconnect and reconnect the power cables and HDMI cables on the back of your TV or the One Connect (OC)
Box, then unplug the power cable and plug it back into the wall outlet.
HDMI
If the external device support 4K UHD or 8K UHD videos, use a dedicated HDMI cable for each resolution.
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