Compaq R6000 - Manual (Page 81)

5-6 Compaq R6000 Series UPS Operation and Reference Guide
4. Disconnect the battery cables. The cable connectors have release tabs on
their sides that must be squeezed to allow the connectors to come free
from the battery.
Figure 5-4. Disconnecting the battery cables
5. Remove the battery pack attachment screws using a #2 Philips
screwdriver.
Figure 5-5. Removing the battery pack attachment screws