i need help

I was installing an external amp om my friend 2004 aztek---i hooked the power cable to fuse box post instead of battery post without disconnecting the battery--i blew something because the radio will not come on-----what fuse or relay controlls the radio---the fuse inside the car is ok--also i put another radio--to c did i burn the radio up--that 1 did not cone on also---whats the problem-----3100 eng--70000 miles