Compaq Evo W8000 Hardware Reference Manual page 73

Battery Replacement
C-2
To replace the battery:
1. Shut down the operating system properly, turn off the computer
and any external devices, disconnect the power cord from the
electrical outlet, and remove the computer cover or access panel.
It may be necessary to remove an expansion card to gain access to
the battery.
2. Locate the battery and battery holder on the system board, as
shown in the following illustration.
Battery and battery holder
3. Lift the battery out of its holder.
Removing the coin cell battery
Compaq Evo Workstation W8000 Hardware Reference Guide