Please do tell. What are some of the other ways?
Sure. There are multiple engine rooms in the Enterprise.
From "The Naked Time": SCOTT: Engineers, man your stations. Engine rooms, report.
One possible access way could be from the large portable machinery side like that opening in "The Enemy Within".
https://tos.trekcore.com/hd/albums/1x05hd/theenemywithinhd484.jpg
Alternatively, we're shown very limited areas of the specific engine room that Riley is poisoned in which opens possibilities of a larger space with multiple paths in and out.
And Riley locked ALL the doors. Scotty just focused on opening one.![]()
Or Riley picked the one engine room that only has one way in
