Dell Latitude C840 - Manual (Page 19)

5. Lift the right end of the keyboard and slide it slightly toward the right side of the computer to disengage the tabs at the left end.
6. Pivot the keyboard and balance it upright on the left side of the computer.
7. Disconnect the keyboard cable and lay the keyboard aside.
Replacing the Keyboard
1. While bracing the keyboard upright on its left end, connect the keyboard cable to the keyboard interface connector on the system board.
1 blank key
2 keyboard
3 right side of computer
1 keyboard cable
2 keyboard interface
connector
3 system board
NOTICE: Position the keyboard/track-stick flex cable so that it is not pinched when you replace the keyboard in the bottom case.