98 explorer audio problems/possible dead or fried speakers/wires

well i installed a new stereo for my girlfriend in her 98 explorer. course having years and years of experience couldnt prepare me for this issue. she told me she had to jump it and it fried the stock stereo. im curious if anyone has ever had the same prob if they might know if it had enough current to blow all the speakers (which i somewhat doubt) or possibly friend the wiring interconnected to the stereo itself or both. any feedback would be greately appreciated, thanks.