Dell Precision T5400 (Late 2007) - Manual (Page 76)

76 Securing Your Computer
Replacing the Chassis Intrusion Switch
1 Gently slide the chassis intrusion switch into its slot and reconnect the
cable to the system board.
2 Replace the computer cover (see "Replacing the Computer Cover" on
page 161).
NOTICE: To connect a network cable, first plug the cable into the network port or
device and then plug it into the computer.
3 Connect your computer and devices to electrical outlets, and turn them
on.
Resetting the Chassis Intrusion Detector
1 Turn on (or restart) your computer.
2 When the blue DELL™ logo appears, press <F2> immediately.