what i would do in your case, i am a little mechanically inclined
take off the kicker panel on the left side of the footwell, there is a screw in the middle right thats a little hidden but its there, dont forget to disconnect the tweeter down there (yeah theres a speaker there)
then track down the cable and try to follow it under the car
im dont remember if you have to take off the underbody plastic panel or if its exposed
and if you cant see anything wrong
next step is to take off you rear wheel, you can do one then the other if you dont have jack stands
unscrew the caliper, 2 bolts behind the caliper, you need a long thick screw driver to decompress the caliper a little to take it off the rotor
then unsrew the bolt holding the caliper ( im not sure if its there or if thats only in the front, but if you look you will deffinitly see it if its there)
then try to take of the rotor, if its a little rusted around the center hub, my technic its to spray WD-40 around it and hit around the rotor a little, not the disk part, and the vibrations will usually get it off
then once you have it off then see where the cable pull and see if you see anything broken or bent.
this might be too extensive but if you would want to sace some money then this would be a good way to go