Question is for a 2002 Sentra....(non-ser, etc..).....long story short, I installed an aftermarket amp. into my friends car....I turn the car on and the amp worked for about two seconds then shut down....I immediately disconnected the amp and tried to start the car but it would not turn over..battery is fully charged and everything else works fine (lights, wipers, etc..)...however, when trying to start the car the only noise I hear is the fuel pump....the accessory/amp on wire is not getting any power...I have checked all the fuses under the hood and dash, all were fine.....please help me diagnose this problem......