Our partners at Brotherhood Instructors, LLC tipped us off to this training video from Instructor 5 Productions. This video demonstrates three different methods for cutting through garage and other roll-up doors with power saws. Two of them create triangular openings and may be more familiar techniques to you. The third is more involved but gives you a much wider and potentially more useful opening.
Or you can always just deploy your idiot, like they did in this video. That’s always an option – not a good option, but an option.