What happens if I press "Stop" in AME?

I'm in hour 16 of a render (H.264, 1 Pass, FML) and at this point, I just want the existing render without waiting the approximately 15 hours still remaining for my two-minute video. 

I've tried copying the existing .m4v file every possible way but AME has it locked up. If I press "Stop" will my existing render still be sitting there in the folder? Can I salvage it from there? Or am I doomed to wait this out and miss my deadline?