Lenovo T560 Manual page 17

CONTROLS LOCK / UNLOCK
This feature allows you to secure the current control settings, while allowing
the user to adjust Brightness or Contrast, so that they cannot be
inadvertently changed. Push and hold the enter button[ ] for 10 seconds;
the message "Controls Locked" appears.
You can unlock the OSD controls at any time by pushing the enter button[ ]
for 10 seconds; the message "Controls Unlocked" will appear.
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