Custom close button for dropdown list

I am trying to build a flyout menu using the dropdown list. I have it working as best I can, but can’t figure out how to make the ‘x’ close the menu after it has opened. To be clear, I simply want to use the ‘x’ as a trigger to close the menu, without adding any custom code. Should I be setting this up in a different way? Should it really be this hard to close these dropdown menus? I’ve read countless articles on here about it, but can’t seem to figure out how to even use a trigger interaction with this setup. Any ideas are appreciated.

p.s. the initial toggle is the square grid button at the top right

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