It showed 2%. It was at the bottom of the list. I'm checking it now and it isn't in the list at all. The day before it died, a call was blocked by avast. Maybe it kept running after the block???
I wonder about the reliability of Android's battery usage chart. Even though avast itself showed 2%, is it possible that avast was interacting with another service, such as Android OS or Android System, and that other service showed the high percentage of drain?