HP ProSignia 120 Maintenance And Service Manual page 92

CAUTION: To prevent damaging the RTC battery cable, do not pull on the battery
cable.
6. Using tweezers, disconnect the RTC battery connector from the system board.
7. Remove the RTC battery.
Figure 5-19. Removing the RTC Battery
Reverse the procedure to install a replacement RTC battery.
Removal and Replacement Procedures 5-21