Since it drains in only nine hours, just disconnect the ground and positive cables, wait over night and then reattach them. If it is dead, then replacing the battery would be a good idea. If it starts up you have something stuck on which is draining the battery.

The positive cable will likely issue a small spark when you reattach it due to the clock draw, but if it is a robust spark with an audible snap, you have something drawing pretty heavy current.

You can begin looking for stuck items by examining the car at night in a dark garage. Anything glowing? I left my glove box door open one night and had a flat battery the next day. Other items are less obvious, like the antenna which would require you to remove the fuse to confirm. Do one thing at a time to isolate the problem area, starting with the suggestions others have made based on their experiences.

Good hunting...

230/8