Battery dies as soon as ignition is turned off

[majon7]

I have a 07 Astra petrol 1.8 hatchback . I was driving last week everything seemed ok . 

I parked out side the house went in for about 10 mins went back into car and it was as if there was no battery in the car there was nothing  no dashboard lights , no clicking ,the remote locking didn't work the battery was totally flat.  I put a charger on the battery the car started and I drove off. I drove for about 30 mins with lights on there was no dimming of lights , no battery light on dash as soon as I turned the ignition off  it went flat again . I have done the fuse test , cleaned the earth connection , checked no lights on , checked alternator all ok . 

Put brand new battery on. 

Any ideas ?