Quickly flashing green LED indicates the screen service restarting. Sometimes it is intentional, like when you e.g. toggle a lockscreen patch in Patchmanager. I don't use the media control patch but I have encountered the unexpected flashing green LED quite a lot. Sometimes, when the screen comes back, my background image is gone. It is always triggered by trying to make the lockscreen do "something" (e.g. just moving it up and down) after applying some patch. Your double tap may fall in this category.