If the switch has no problems and the power is still not turning on, then you should check that power is reaching the terminals on the electric pump. You will need to do this carefully.

First, while the device is disconnected from the mains, you would partially push back the insulation covers on the terminals so you can access them with multimeter probes.

Next, plug in the device and switch it on. Set the multimeter to read the voltage, then place the two probes on the terminals. You should get a mains voltage reading.

If there is no reading and you have already checked the switch and the mains power cable, then it is possible that one of the cables from the switch to the motor is damaged, so you would want to check for the continuity on each of these cables.

If the power is reaching the electric motor and the device is still not turning on, then there is likely a problem with the motor itself, and it will need to be replaced. You can be sure of this by checking for continuity within the motor.

With the device still disconnected from the mains, disconnect the terminals by gently pulling them off.

Put the multimeter on continuity and test for resistance within the motor. If there is no continuity, it means that the motor is damaged internally and needs to be replaced.

The motor is held in place by three screws. You need to undo all of these. You then take the entire motor out, including the fan unit, which is attached to it.

To put in the new unit, simply put it in place and put back the screws.

There are some rubber washers between the pump and the casing, which stop the vibration. Make sure those are in place.

Reconnect the two terminals with the wires coming from the switch.

You can now test it to make sure that it is working.