How to dismantle SK-8165 Alienware Keyboard

I am trying to open an old keyboard for cleaning and attempt to repair a key. I have removed the screws and when attempting to open the case it separates fine on three sides, but there seems to be a hidden latch or something on the top edge, just to the left of where the cord connects, which wont allow it to separate. Any videos I’ve found show the case separating with ease. What am I missing and how can I get the case to separate?