I have been trying to fix my dad's washing machine for more than a week--it originally got stuck last Thursday with an error message that came on the screen and the door locked (it's a front loading washing machine).
I read up about the error, which is E01 -> F09, which means generally something like "problem in the draining process"-- could be a clog or a busted pump, or apparently even too much soap can cause it.
I managed to break the handle of this drain plug cap because I was using the metal part of the pliers to turn it, like I saw in some youtube video, and it cracked and started leaking, so I ordered a new piece for that, which came wednesday. Oops!