I would double check that the screw connector for the pump is free of corrosion and salt crust, the added resistance or a short caused by salt or water can cause this. You can test the pump itself by touching the pump wires (blue and brown bare wires of the pump to a 9V battery. Polarity does not matter, if the pump does not run we can be sure it is dead and the cause of the problem, if it runs, it is a grey area, it may work but need more power than the controller will allow as it is failing. Unless the pump is used with kalkwasser or an additive it should not need cleaning and cannot be opened or serviced. If it was used with kalk or a similar calcium supplement, it may lock up and a vinegar soak may help.