Black screen on device after build. How to debug?

I have had a project which was being built without issue for a week. Then, it stopped working. I get the Unity splash screen, and then blackness. I can’t get any information about what has happened. The black screen happens on both iPad 4 and iPhone 4.

The only real clue I have is that I tweaked the Quality level settings and added some code that allows the user to change the quality level on the fly. I can’t imagine how that code could be getting run, but perhaps the default quality settings have something that is incompatible with iOS devices, resulting in nothing being rendered. Just in case, I’ve attached a screenshot of the current default quality setting.

Anyone have any thoughts? Any suggestions on how to get more information?

Disable all objects in your scene minus the camera and try to see exporting and then activating your items one by one … if it stops working on that will be failure …
Luck

In the meantime I’ve confirmed that it does have to do with quality levels. Setting the default quality level to the lowest one made the game show up, and then increasing the quality level made it go black.

I realized then that I have a SSAO image effect on the camera which is enabled/disabled based on the quality level. I’m making one more build to test this hypothesis, and if confirmed will report back. The only thing confusing this diagnosis is, I think SSAO was enabled on the earlier (working) builds, although I could be wrong about that.

Does anyone know offhand if SSAO is at all compatible with mobile? Or am I just going to have to forget having SSAO?

Confirmed, SSAO was causing the problem. with great sadness, removes SSAO from the camera completely

And realtime shadows are causing huge framerate dips as well, so it looks like we’ll have to do without those as well.