Error Code SCREEN LOCKED

Screen lock is active — a locked key was pressed or screen is in partial lock mode.

? What Causes This

Screen lock feature is enabled (function 0670) or a locked key was pressed during partial lock mode.

Press any unlocked key while SCREEN LOCKED message appears.
Or wait for message to disappear.
To disable screen lock, access advanced function 0670 and set to option 0 (unlocked).

Source: page 18 of the official manual

From the manual

This error code appears in: