HP t620 PLUS Hardware Reference Manual page 17

4. Disconnect the power cord from the power outlet, and disconnect any external devices.
CAUTION: Regardless of the power-on state, voltage is always present on the system board
as long as the system is plugged into an active AC outlet. You must disconnect the power cord
to avoid damage to the internal components of the computer.
5. Remove the computer from the stand.
6. Lay the unit flat on a stable surface with the right side up.
7. Release the latch (1) on the left side of the rear I/O panel, rotate the I/O panel (2) to the right,
and then lift it off the computer.
8. Move the access panel latch (1) to the left to release the access panel.
9. Slide the access panel (2) approximately 6 mm (.24 in) toward the back of the chassis, and then
lift the panel off of the computer.
Removing and replacing the access panel 11