HP ProBook 5220m Notebook PC - Manual (Page 73)

3. Slide the battery lock (3) to the right to lock the battery into place.
To remove the battery:
1. Turn the computer upside down on a flat surface, with the battery bay toward you.
2. Slide the battery lock inward. Then slide the battery release latch on the left (inward) (1) to release
the battery.
NOTE: You can identify the battery lock by the red marking on the latch.
3. Remove the battery (2).
Using battery power 61