WOW, and the radio was working?
It's a bit hard to tell from the photo but that almost appears to be more of some type of chemical attack since the shielding where it's torn open doesn't appear to be blackened. The edge of the radio case also appears to be corroded. But maybe that's just from the camera flash. There really shouldn't be any current to the antenna cable - unless something inside the radio is shorted.
2011 Chevy Silverado Crew Cab 4X4
2009 210 WBS