In this case, the output has been shut down due to the shutdown signal received through the external contact.
How to clear TRBL-19:
If the external control logic is set to OPEN, short-circuit between pin 9 and 10 of the SIGNAL I/O connector, and then turn on the POWER switch.
If the external control logic is set to SHORT, open the connection between pin 9 and 10 of the SIGNAL I/O connector, and then turn on the POWER switch.
For the details, read the user’s manual – chapter of SIGNAL I/O Connector – Controlling the PCR-LE through external contacts – Shut down the output.