1964 Chevy Corvette

I RECENTLY PURCHASED A NEW BATTERY FOR THE ABOVE CAR. AT THAT TIME, THE TECHNICIAN SAID ALL OF THE CHARGING COMPONENTS WERE WORKING CORRECTLY. I JUST WENT OUT TO DRIVE AND THE BATTERY WAS SO MDEAD THE HORN WOULD'T WORK. IT HAS BEEN A COUPLE WEEKS SINCE THE CAR HAD BEEN DRIVEN. I BELIEVE THERE IS A BATTERY DRAIN SOMEWHERE BUT AM NOT SURE HOW TO PROCEED.

THANK YOU