Dimmer module only works when hard powered on

We have CEM3 and Sensor 3 dimming modules, and one of the dimmers is constantly showing as an AF Bkr Trip fault, unless I physically switch the module to 'on' in which case it gets power as it should. Every time I try to clear the fault it re appears a few seconds later. The circuit breaker doesn't trip and it is only happening on one of the dimmers, not both in the module.

I removed the module and all seems to be fine, is there anything I can try at the moment?