Dell Inspiron 15 3521 Service Manual page 65

Steps
1. Disconnect the following cables from the system board:
a. I/O daughter-board FFC
b. Power-adapter port cable
c. Keyboard FFC
d. Keyboard-backlight FFC, if applicable
NOTE: This step applies only to systems shipped with a keyboard backlight installed.
e. Touchpad FFC
f. Hard-disk drive FFC, if applicable
NOTE: This step applies only to systems shipped with a 2.5-inch hard-disk drive installed.
Removing and installing components 65