Dell Inspiron 13z (N311z, Mid 2011) - Manual (Page 14)

14 Battery
Replacing the Battery
1 Follow the instructions in "Before You Begin" on page 9.
2 Place the battery in the battery bay and press down until it clicks into
place.
3 Ensure that the two battery release latches are in locked position.
1 battery 2 battery release latches (2)
2 1