I haven't used my Pure Freedom trolley for about six months or so (since I've now moved to a van mount). I tried to get it working today however when I switch the controller on the LED display flashes between the flow rate, PS & Bat. I have re-calibrated but still get the same issue. The battery is fully charged. The trolley has been sitting in a dry garage over this time. NB: The hoses into & out of the pump look to be clear & I get this problem whether I have the WFP connected or not... Any ideas?