Dunno if this would work for you, but did some digging around.
From another forum, posted by Da_Coynul:
After reading that some applications implement a "partial wakelock" which prevents the CPU from going to sleep, I decided to get rid of all of my installed apps and start fresh. I did a factory reset and sure enough, no more overnight, power off battery drain. I am glad I didn't panic and return or exchange my phone. I hope this saves someone else some time and aggrevation as well