Battery going dead

[ReefShark]

II have seen posts about Trailblazer batteries going dead. I have just started having that problem with my '03. I have a 3 mo old battery, posts clean and if I don't drive it for 2 or 3 days it goes completely dead.
Yesterday I had the battery checked by auto zone where I purchased it, and the battery tested good and alternator was charging fine. Since the battery was in warranty, I had them replace it and I went to a HD battery.
Now my question for those that have had this problem, is there something that could be draining the battery overnight. Everything is off, key out. I did have the dash pulled to change the actuator cam two weeks ago.
I remember reading how to test to find out if there is an open circuit, but forgot what it was.

[Bullethole]

My 03 did the same thing this past weekend. Battery checks good. I smell the computer. It is supposed to turn things off as rundown protection but maybe it is not happening like it is supposed to.

[jcscofie]

Has anyone seen a solution on this ? - my 2004 just started doing the same thing... with two years left on a 6 year battery and battery and alternator tested ok