The pressure washer should be turned off. Dry it and attempt to do it again. If the test fails then you should bring the vehicle to a repair center, or examine the engine on your own. Take a look at the spark plug, engine as well as the carburetor, among other components. If they were waterlogged, you'll need replace them. Pressure washers with electric motors can be more difficult to repair. Find an option to reset it and test the reset. If it's not there or it doesn't work then it's likely that there's an electronic component in the wrong place. It is best taking the device to a repair center.