I have an error code of U3 in the top drawer

Error code U3 could mean the drain pump is blocked.

Remove the trays and the impeller arm. Empty the water with small container or towel. Open the filter plate and drain filter. Get the motor out and check the cavity for any rubbish. Also use a stiff thin wire to clean the passage between drain filter and motor cavity. The instructions for removing the filter plate and motor assembly are in the user guide.
Good luck