The H20 error is an indication of a problem with the water supply to the machine. The water is not filling.
The wash cycle will not start when there is an H20 error and water is not filling. Check if the water supply is turned on/connected properly.
To fix this problem check the taps, inlet valves, hoses/pipes and make sure there is no leak, blockage, misconnection or restriction in any of these which may stop the water supply/flow.
Also make sure that the water presure is good enough. If there is any blockage or leak or misconnection in any of the pipes/valves/hoses you will have to fix it for easy and continous flow of water. Also check the inlet valve filters.
Make sure that the tapes/pipes are not kinked and they are open properly for free flow of water to the machine.