F&P DW820 beeping and pump stays on - no lights?

I have a F&P DW820 that started beeping, display lights flashed and the water pump was running dry. I unplugged and replugged an hour later and still the same but now with no lights. Any ideas what the fault is? I 'flushed' the cavity at the left rear, and dried it for an hour wit the hair dryer. No difference. Could it be a switch fault that tells the water level? ie. the pump is staying on but all the water has been pumped out.