That should open the door however, if the issue is still there then please try this:
Please unplug the appliance and remove the bottom front flap.
Keep some beach towels and shallow container under the filter.
Then rotate the drain pump filter anti clockwise to open, clean it completely and make sure it is not clogged.
Now, with your fingers check if impellor rotates.
Then you will see a pull tab next to the filter, pull it to open the door.
Please let me know how it goes.
Please do not hesitate to ask any follow up questions.
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Have a wonderful evening.