Dell Precision 3520 Owner's Manual page 28

a. Release the WLAN and WWAN cables from the routing channels [1].
b. Disconnect the speaker cable from the connector on the system board [2].
c. Lift the latch to disconnect the backlight cable (optional) [3], touchpad cable [4], pointstick cable [5], and keyboard cable
[6] from the connector on the system board.
4. To remove the chassis frame:
a. Remove the M2x3 (5), M2x5 (2) screws that secure the chassis frame to the [1].
b. Lift the chassis frame away from the [2].
28 Disassembly and reassembly