Stuck Inside Airship in Batman: Arkham Knight

I know what reputation this game has acquired but right now, performance wise it runs quite good on my system at 1440p. However, my issue is that on my second visit on the Airship (Main mission), after opening a door a fell into the airship with no possibility to get back up.

The game saved that point as a checkpoint and I can't reload a different save. From what I have read this is a common issue but most suggest reverting a backup save (I don't have one).

But I understand there is a key combination you can press while on the main menu (while highlighting your save slot) to reload a previous checkpoint. Can someone please write this key combination, or another method to reload a previous checkpoint.

P.S. Looking into Documents in the folder of the save location I found 4 files BAK1Save0x0, BAK1Save0x1, BAK1Save0x2 , profile.bin. which are all related to save slot 1. I don't want to restart since I am at 70% completion.
 
Solution
https://steamcommunity.com/app/208650/discussions/0/530646715639145105/

If you would like to load an even earlier save or checkpoint, back out to the first menu when you start the game and before you select your save slot, highlight your save slot, and press either the Minus Key (-) on your keyboard if playing on PC, the shoulder buttons on Xbox One, or the L1/R1 buttons on PS4, and hold the button for ten seconds. Once the option changes to view backup saves, select your save. This will allow you to load one of your recent saves instead of your current save

http://support.wbgames.com/link/portal/24022/24028/Article/1061/How-do-I-return-to-an-earlier-save-or-checkpoint-in-Batman-Arkham-Knight
https://steamcommunity.com/app/208650/discussions/0/530646715639145105/

If you would like to load an even earlier save or checkpoint, back out to the first menu when you start the game and before you select your save slot, highlight your save slot, and press either the Minus Key (-) on your keyboard if playing on PC, the shoulder buttons on Xbox One, or the L1/R1 buttons on PS4, and hold the button for ten seconds. Once the option changes to view backup saves, select your save. This will allow you to load one of your recent saves instead of your current save

http://support.wbgames.com/link/portal/24022/24028/Article/1061/How-do-I-return-to-an-earlier-save-or-checkpoint-in-Batman-Arkham-Knight
 
Solution

I fixed the issue with the free roam mod:
https://www.youtube.com/watch?v=dXeJNHHv-qY
I seem to get no voice acting in-game (probably a compatibility issue with the version of the game as I didn't installl the latest mod version ) but after deleting the mod (after getting a different autosave) it worked good.
Just changed to another character and back to Batman. It worked well. Thank you for the links anyway.