Dell XPS 15 (L521X, Mid 2012) - Manual (Page 13)

7 Lift the connector latch and, using the pull-tab, disconnect the battery-LED-board
cable from the system board.
5
4
3
2
1
1 connector latch 2 pull-tab
3 battery-LED-board cable 4 battery-LED board
5 base-cover assembly
8 Remove the battery-LED board from the base cover. See "Removing the
Battery-LED Board" on page 15.
Removing the Base Cover | 13