Buzzing Sound in car

[Lancerboy1]

today my mechanic pull out my car wire, from ecu to my invec2 gearbox console, just to see how it is connected. He never cut any wire but i think he never put back properly. after i left, i realised my cross-over for my speaker are not connected, then i pull away my carpet again and connect back the cross over, then i turn the key to ON, buzzing sound very loud... sound like fuel pump but i remembe my fuel pump not this LOUD> what happened> pls help!!!