Hmm, it's been a while but I thought I closed the elevator door once you walked out and triggered it. I reckon you didn't do that and wanted to go back up again?
What you can do is add this save file to the other ones: https://www.dropbox.com/s/emkfv5lpyopni4b/SD_EndGameSaves.sav?dl=0
You should then be able to choose to explore the SD-01 starting from the bridge. It shouldn't impact anything important and you can then head down that elevator when you're ready and continue the story.
Sorry about that, some of the things are complicated, perhaps over-complicated by my (at the time) lack of knowledge but I'm sure this should be a adequate fix for you particular situation. Let me know if this did it for ya!!!
You can find the save files here:
"C (Or your windows install drive):\Users\(Your user name)\AppData\Local\STARDROP\Saved\SaveGames"
Thank you for the file - I was a bit confused at first, but then I noticed under "Chapter Select" there was a new option for "SD-01 Unlocked" - which put me right at the start of the bridge.
Yes, I thought it would be an optional side area since i was able to figure out how to unlock the elevator before exploring more than 1/3 of the bridge. When I went down the elevator and saw the area, before i stepped out I realized "this looks like Story content" and tried to go back. When the elevator was marked as unusable, i thought i could reload my manual save made before going down the elevator. Didn't realize it auto-saved when i took the elevator.
I had managed to find a video of the ending, as I wasn't sure If I would get a reply - but very much appreciate your assistance.
It was much better to be able to finish what I had started for myself, and both my wife cried at the ending for a 2nd time. :)