If the power is on and unit still it does not work or does not display anything, then the internal device fuse may be defective or burned.
In this case, open the device, remove the old fuse and check it.
Replace the defective fuse with a new one, locate the external source of the error (eg. Pump) and exchange.
Subsequently, the controller and check the function of the switch outputs in manual mode.
Only use the supplied spare fuse or a fuse with the following characteristics: T2A 250V