Introduction
Many of the things that go awry with dishwashers stem from user error, so the good news is that they are often just as easy to rectify as they were to cause in the first place! Compared to many appliances and household equipment, dishwashers are actually reasonably simple devices, so let's take a look at what might be happening if your dishwasher isn't powering on.
Dishwasher won't power on or won't operate at all
Check the electrical socket/outlet into which your dishwasher's power connector is plugged. Although it sounds silly, check that the socket is switched on and whether it is receiving power (you might plug another appliance into the socket briefly just to test it). If the socket is good and supplying power correctly, move on.
Check the fuse inside the dishwasher plug to ensure that it has not blown. If it has blown, always consider that something will have caused it to blow. This should always be investigated, else you risk it blowing again, or worse, overlooking a more serious issue that beyond the scope of this guide.
Check the fuse or circuit breaker at the consumer unit for your electricity supply, where the circuit supplying the dishwasher is located. Has the breaker tripped, fuse blown (if it's an old style fuse board) or has an RCD unit that covers the circuit tripped? Again, unless you are aware of the reason for these things, you should consider investigating the underlying cause with a qualified electrician.
Make sure that the dishwasher door is correctly latched. Dishwashers are designed not to operate if the door is open, to ensure that there is no risk of flooding your room or gaining access to moving parts or hot water. A kitchen utensil or plate might be obstructing the correct closure of the door.
Finally, most dishwashers won't operate if they cannot bring water into them using the cold water inlet. Check that the supply pipe is not blocked at the filter or kinked so that flow is prevented. Make sure that your home has water and the supply is not isolated or interrupted.