E4 error code means water has overfilled or leaked into the base.
Pull the dishwasher out and lean it backwards and see if water runs out from the bottom. You may need a towel for that part.
Once the water has drained out the this should reset the anti flood switch in the base and clear the error code.
Then retry the dishwasher and see how it goes from there.
If it does it again then theres a leak in there which you need to find and fix.
To do this you need to remove both side panels by undoing the screws at the back and then on the front when you open the door. Then you can see underneath the appliances and access the hoses.
But fingers crossed this may be just an overfill inside and tipping the dishwasher clears it out.
If you need anymore info just get back to me.