Hi,
Can I suggest you do a complete rewire, taking into account.
Keep all 24V switched and power wires together and keep them away from any input to the relays and the wiring between them and the Nano.
Keep all wiring between the relays and the Nano together.
Keep all wiring between the sensors and the Nano away from other wiring.
The relays circled in red and blue, turn them 180degrees, so their 24V wiring does not crossover input wiring as in the red circle, and away from the Nano in the blue circle.
How have you got the Nano terminal board fixed the the cabinet backplane?
Thanks.. Tom.. 