HP ProOne 400 G1 All-in-One Hardware Reference Manual page 32

9. Remove the three screws securing the fire enclosure shield to the chassis, and then rotate the
shield out of the chassis.
Figure 2-22
The battery can now be seen to the right of the fan.
Figure 2-23
10. To release the battery from its holder, squeeze the metal clamp that extends above one edge of
the battery. When the battery pops up, lift it out (1).
26 Chapter 2 Hardware repair and upgrade
Removing the fire enclosure shield
Locating the battery