Without the information requested in my previous response, I can only give you a general answer, but I hope this helps.
E4 error code as you already know indicates that water has leaked in the base of appliance and activated the anti flood device. Please try this to solve the issue:
You will have to unplug the appliance and pull it out, then tip it backwards by around 45 degrees so excess water drains off completely.
After you have done this, check the drain hose where it connects to house drain and make sure it is not clogged.
Then please clean the mesh filter from inside and make sure it is not blocked.
Now, reconnect everything and plug it back; select any program.
It should work however, if the problem occurs again you will have to check what is causing the leak.
Alternatively, as it is under one year old and still in warranty, you may contact Beko to book in warranty repair.
Please let me know if you need me to clarify anything or if you have any additional questions-I am happy to help!
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Have a wonderful day.