M8, i think i find the problem.
I turned profiles ON and set a wifi trigger to two profiles. After it the phone drain as much battery as yours on deep sleep.
Turning it off made the drain back to normal.
It isn't a kernel thing really. Do you h...
I had the "-504" issue too twice in a row.
Aftet reinstalling a backup, it seems that this error occurs after having installed the ZIP installer fort Xposed framework for lollipop
I did not investigate furthermore, but without this installation ...