it could be grounding out...but usually when one speaker grounds out it causes them all to be silent...
if you havnt already done so...take the speaker out and test the resistance with a multimeter... it should read 2.0 Ohms, if it is a BOSE.(also possible for 4Ohms) the speaker magnet should indicate what the OHM of the speaker is.
if all is fine with the speaker it could be the channel on the BOSE amp that is shot. hopefully thats not the problem, becuase it will cost a fortune to replace. unless you know some one that works for the dealer.
good luck.