oil change query

Hi, my first oil change, superb bike.
I know there is a second drain plug concealed inside the sump. When removing the second plug, my 5mm hex slipped and would not unwind it, I bottled and simply changed the oil without draining the second part of oil. My info (PDF file and youtube) says it needs undoing with a 5mm hex-has anyone found this different-maybe a torx or a bigger hex?
Thinking back, I should have looked up using a mirror-but now I have refilled and replaced the plug, a half done oil change so before I redo it, thought I'd ask if anyone else had similar?

I have the same problem and my fix is unscrew the oil filter about three turns and hit the start button and shut engine off in about 3 seconds and do this about three times and you will have pumped most of the oil out left in the engine.