Ceiling Repairs – How to Plug a Hole in the Ceiling

I'm going to take a wild guess that the previous home owner put the blanks up because they had the same problem and didn't want to fix it. You likely have a short circuit and need to track down where the short is occurring. I'd remove the bulb from the fixture, unhook each of the wires that you connected before, and use a multimeter to test for "continuity" between the wires on each run (e.g. hot to neutral, hot to ground, neutral to ground for the line to the switch, for the light fixture without a bulb, and anywhere else that was previously disconnected). If you don't have continuity with a simple low voltage tester, then the problem could be arcing that only occurs when 120V is applied. Either way, get this fixed before turning the breaker back on with this fixture wired.

Unfortunately, as with most questions like this, you're going to have to talk to an engineer. A bunch of amateur DIYers on the internet, is not the proper resource for this type of information.

You're making a major structural change to a building, and you don't want it to cause property damage or personal injury. The "correct" and responsible thing to do, is to seek the advice of a trained professional.