in my 91 accord it came with no deck so i ended up buying one i wired everything up plugged it in and no power. checked all fuses. tryed in my friends accord and it powered on. i did notice that the cars wire harness the black ground wire is cut and just hanging off conected to nothing. could that be the problem?

 

That's the problem. If your hu is not grounded, it will not get power. Properly secure a ground to the chassis of the vehicle.