11.8 is low, really low. What is the voltage at the battery terminals. Should be 12.6 or better.

You could try running a jumper from the batter + to the side of the ballast that reads 11.8 right now and try to start it. If it runs remember that you won't be able to shut it off till you pull the jumper. and it will narrow theisue down to before the ballast.