The most common cause of a E20 fault is a blockage in the draining circuit.
You've already done some of this but it will help if you follow each stage.
It's a lot of work but try the following.
Check the drain hose where it connects to the house drains.
If onto a connection, take the hose off and check both for a blockage.
If ok, you'll need to manually remove the remaining water from the machine.
Put a shallow dish in front of the filter/pump cover. (Bottom front of the machine)
Slacken the cap a little to drain the water.
Tighten the cap to stop the water when you need to empty the container.
(If you pull the machine out and tilt it rearward, you can get a larger container in place for a while).
Once the machine is empty of water, take the cap off.
Clean out any debris in there.
Once cleaned out, take the laundry out of the machine.
With the cap off, put the machine on spin only.
Look into the open filter (listen at the open filter) to see if the pump is running.
(You should see the pump impellor rotating)
If the pump isn't running, unplug and check to see if there is something jamming the pump impellor.
If the pump is running, refit the cap and try the machine again.
Let me know what you find or if you need more help.
Hope this helps
Let me know how it goes or if you need more help