Matrix-UPS is not providing any output power to the receptacles on the rear of the UPS.
There is an ON/OFF circuit breaker switch located on the back plate of the Matrix-UPS IU (Isolation Unit, lower half of the Matrix-UPS) just above the NEMA L14-30 receptacle. This breaker controls the UPS output to the L14-30 receptacle (as well as the NEMA 5-15 receptacles on the Matrix-UPS 3000 model only). On the Matrix-UPS 5000, this switch controls the L14-30 receptacle only. If the Matrix-UPS is powered on and there is no output to the L14-30 receptacle (or any of the 5-15 receptacles on a Matrix-UPS 3000) check this switch to ensure that it is set to ON (to the right). This symptom is often experienced on a new installation.
Close the breakers to restore power to the receptacles. If the breaker has tripped while the unit was in service, this was due to an overload to the circuit by loads downstream of the Matrix-UPS. Evaluate the circumstances and correct by reducing the number of connected devices.