Get the radio and take it apart. If it works there should be a resistor on the board. You can cut this or just remove the batters. If the batteries are good remove them an you can use them to make LED Throwies!
So, now strip the wire on the head-phone jack. There should be what appears to be a red and blue wire. Solider the red wire to the terminal on the little speaker on the left; blue on the right. Take the solider gun and melt a little dent on the side of the plastic. The cord will go through this. Now put the back on and screw back together. * other 2 mods coming soon*