"Chassis intrusion connector (4-1 pin CHASSIS)
This connector is for a chassis-mounted intrusion detection sensor or switch. Connect
one end of the chassis intrusion sensor or switch cable to this connector. The chassis
intrusion sensor or switch sends a high-level signal to this connector when a chassis
component is removed or replaced. The signal is then generated as a chassis intrusion
By default , the pin labeled “Chassis Signal” and “ Ground” are shorted with a jumper
cap. Remove the jumper caps only when you intend to use the chassis intrusion
detection feature. "
Sounds like you removed the jumper. Also sounds like all you need to do is put the jumper back (or find another jumper to replace it).