Shut down the computer
Unplug the power cable
Remove the laptop battery if applicable
Press and hold the power button for a few seconds
Open the computer case or access panel
Locate the CMOS battery on the motherboard
Note the battery orientation
Release the battery clip or holder
Lift the CMOS battery out carefully
Avoid touching other components
Store the battery safely if reusing it
Reinstall the battery by matching the original orientation if needed
Close the case or access panel
Reconnect power and turn the computer on