The walkthrough says this:
Look close at the Allen wrench in inventory. Click the hand icon at right to isolate the wrench required.
Use the Allen wrench with triangle on the lock. The lid opens to show another cover. Check the screws at top right and top left to note that it has hexagon indents. Isolate the hexagon tipped wrench in inventory. Use it on the top right and top left screws.
If this does not help at all, let's wait for another player (unless I can find more advice about this).