HP ProOne 600 G3 21 inch All-in-One Business PC Hardware Reference Manual page 43

If your computer model is a ProOne 400, place the EMI shield onto the chassis and use a flat blade
●
or Torx screwdriver to fasten the screws to secure the EMI shield.
6. Install the access panel.
For instructions, see
7. Turn on the computer.
8. Reset the date and time, your passwords, and any special system setups using Computer Setup.
Replacing the computer access panel on page 29.
Replacing the RTC Battery 37