car not starting

[panda88]

hi everyone,
i am having a bit of a problem with the car, i just installed a sub and a sub amp, and now the car is not starting. At first the car had no power whatsoever, but i disconnected the negative terminal off the battery and reconnected it, after this the car has all electrics, but when i turn the ignition to start, it cranks once and nothing happens and all the power goes again. If i disconnect and reconnect the battery again, all the electrics will work again but the car still won't start.
Any advice or suggestions would be graetly appreciated,
thanks,
-michael

[StoneX]

What happens if you disconnect the amplifier? Remove the item that caused the problem and see if it goes away.

[dijm8]

hav u checked fuses??? just incase u blew any?

[CANYONERO]

sure you battery hasnt died??

[the executive]

are you tightening the terminals up??? or leaving a lil loose