I upgraded my KA1 to the latest firmware. The battery doesn't seem to be discharging quickly but with the light set to auto I saw it fluctuating over and over between 9% and 13% up and down over and over again. I finally disabled auto lighting. It was only at one setting for a little under a second before it would switch to another level.
I made a video (shared with Kobo) showing the light setting increasing rapidly while in a well lit area.
https://www.dropbox.com/s/mb9q5a44jn..._1430.MOV?dl=0