Sounds like you'll have to pop the radio out of the dash (look to see if the antenna is even connected to the radio). Not sure which brand/model of radio you have, though.
I've seen two methods of radio removal:
- One uses two "hoops" (found in the Thor bag). Push the hoops into the holes on the front of the radio and pull it out.
- The other uses flat pieces of metal (about the size of an Emory board). These push into two holes on either side of the radio (they release a catch, then the radio can be pulled out)