You don't need a lawyer at all to invoke your
MAGNUSON-MOSS WARRANTY ACT
http://autos.aol.com/article/warranty-and-aftermarket-parts/
"Under the provisions of the Magnuson-Moss Warranty Act of 1975, an automotive dealership/carmaker cannot void your warranty because your vehicle has been modified with aftermarket parts. They (the manufacturers) have to prove that the failure was the direct result of the installed aftermarket part. Unfortunately, too many folks have gone to a dealer to have warranty service performed on their modified vehicle only to have the dealer refuse to cover the defective items. The dealer usually states, that because of the aftermarket parts installed, the warranty is void (without even attempting to determine whether or not the aftermarket part caused the problem).
This is illegal...period.
The Original Poster just needs to print a copy of the act out and go confront the dealer and BRP. Them saying you voided the warranty and refusing to work on it to determine the actual cause of damage is
ILLEGAL.
I would also contact 2 brothers and tell them what is going on. They have dealt with this before I'm sure and will have some good pointers on how to proceed. They can provide technical information on how their system works and what it *could* have done and what it *could not* have done pertaining to damage.