Any answers you'll be able to get to this will be wild guesses unfortunately, without being able to lay hands on the equipment in question with some test gear to find out what's gone wrong. That said, my guess from your description is that something went wrong in the power supply, since it seems to affect all modules, not just a specific one. I'd guess that using a 12V input instead of the 15V intellijel calls for meant it pulled more current from the input to make up the power difference, and as you loaded it up that accumulated too high and cooked something.
EDIT: oh, or it's also possible that the 12v universal adapter you used might not have been able to supply the current the rack wanted and cooked that adapter instead