Dell P2720DC Service Manual page 7

Use a Philips-head screwdriver to remove 3 screws
for unlocking the bezel and the middle frame.
S10
(No.1~3 screw size=M2X2.5, Torque: 6± 1kgf.cm)
Use a Philips-head screwdriver to remove 3 screws
S12
for unlocking the key board and the middle frame.
(No.1~3 screw size=M2X2.5, Torque: 6± 1kgf.cm)
Use a Philips-head screwdriver to remove 1
screws to remove the USB board. Disconnect the
S13
cables of the USB board
(No.1 screw size=M3x6, Torque=4± 1kgf.cm)
The USB Board
7