You say that you used the relay in the Cerbo to drive a contactor, bit did you consider the surge voltages and make sure you had a contactor with protective diodes to prevent Cerbo relay damage. You should tell your colleague to set Relay 1 to manual operation, disconnect the contactor then test for resistance on the NO and common terminals when the relay is on and off to make sure it is working. You may have damaged the switch part of the relay, many people have done this when driving a contactor without using a proper contactor or adding extra diode.
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