Rtc Battery; Shut Down The Computer. If You Are Unsure Whether The Computer Is Off Or In Hibernation, Turn The Computer On, And Then Shut It Down Through The Operating System; Disconnect All External Devices Connected To The Computer; Disconnect The Power From The Computer By First Unplugging The Power Cord From The Ac Outlet And Then Unplugging The Ac Adapter From The Computer - HP Pavilion 17 Maintenance And Service Manual