Is the game played through the mobile web browser, or in a native wrapper like phonegap?
A black screen could be caused by the wrapper failing, or maybe by a memory failure (too big assets?)
What could be done to rule out a logic bug would be to just make a simple C2 app (like something that displays a countdown), If it displays correctly, it means your logic is the problem. Else, it means it's either C2 or your eventual wrapper, or memory.
You could also test with a simple capx with no event (so no logic bug) but with a lot of images. To check if it could be a memory issue.
In any case, not having access to a console will limit your research.