Switch on the power and check, on the three-phase version, that the motor is turning in the correct direction; this should be in a clockwise direction, looking at the motor from the impeller side. If it is turning in the wrong direction, invert the connections of any two wires on the terminal board, after having disconnected the pump from the power mains.
We recommend you read the instruction manual of the GardenJet, GardenInox, GardenCom (also available in our DNA software), which contains a table listing the most common errors and their solutions. Our Garden Jet, Garden Inox, Garden Com self-priming centrifugal pumps are Jet, JetInox, JetCom pumps with some assembled accessories as a standard feature, so please refer to the respective manuals (and their FAQ) for additional information.