HP TC4400 - Manual (Page 106)

Removal and Replacement Procedures
Maintenance and Service Guide 5–23
9. Lift the rear edge of the keyboard 1 until it disengages from
the tablet PC.
10. Slide the keyboard forward 2 until it rests on the palm rest.
11. Release the ZIF connector to which the keyboard cable is
connected and disconnect the keyboard cable 3 from the
system board.
12. Remove the keyboard.
Removing the Keyboard
Reverse the above procedure to install the keyboard.