Well, if you did fry all 3 lnbs from shorting, than it is possible, you shorted the switch, which in turn shorted the LNBs (but I could be wrong, I am NOT a D* tech), that being said...
You should try a new cable (if you already did not) to make sure there isn't a problem with the coax being stretched (which shortens the center lead and would cause issues).
Is the dish grounded with a grounding block to the homes ground, is so, did you test the ground to make sure it was not hot? As that could fry it as well, either way, you should check the ground to be sure, since if you do get 3 new lnbs and the ground is still hot, it could recur.
And remember always physically unplug any receivers from the power outlet before messing with the coax.