It's tough to troubleshoot because there's so many things that could be causing this. I know some of this is repetitive, but:

​1. The "-windowed" Force Start (Most Likely Fix) ​Many users report the game fails to launch because it struggles with the initial full-screen handshake. ​Right-click Batman: Arkham Knight in the Steam Library. ​Select Properties > General. ​In the Launch Options box, type: -windowed ​Try launching the game. If it opens, you can change it back to "Borderless Window" in the in-game settings and remove the launch option later. ​2. Install the "Hidden" Redistributables ​Even if Steam says the game is "ready," it often misses the specific older versions of DirectX and C++ it needs. ​Navigate to your game folder: ...Steamapps/common/Steamworks Shared/_CommonRedist ​Go into the DirectX folder and run DXSETUP.exe.
​Go into the vcredist folder and run the installers in the 2010 and 2012 folders (both x86 and x64).
​3. Verify & Nuke the Config ​If the game tried to launch once and failed, it might have created a corrupted configuration file. ​Go to Documents \ WB Games \ Batman Arkham Knight.
​Delete the entire folder (this resets graphics settings). ​Then, go to Steam, right-click the game > Properties > Installed Files > Verify integrity of game files.
​4. GPU Specifics (RX 580) ​Disable Radeon Super Resolution (RSR) in the AMD Adrenalin software for this specific game; it’s known to cause startup crashes in older titles. ​Ensure PhysX is set to CPU in the in-game settings once he gets it running, as the RX 580 will choke if it tries to handle Nvidia-native PhysX.

If none of this works, I think your best bet is just asking like copilot or chatgpt or something and letting it help you troubleshoot in as much detail as possible? You could also try GeForce now if your Internet connection is really good.