Have you reached out to reputable elevator companies in your area? And by reputable I don't just mean big brand names. if you are in N America it needs to be inspected by your local AHJ. If it has been out of service for 15 years you probably don't know exactly why.
you need qualified people who know what they are doing to go over it before an inspection.
All that being said, did you try reaching out to Otis for prints? you don't need to say it has been shut down but just that you are a building owner and your contractor asked you to get prints