Might try that it's very annoying left overnight it was at 39 just checked and its now 15. No apps running, even turned WiFi off. Something not right here. Very sad as otherwise it's briliant.
Hi, was having exactly the same issue with my R5 as well. Did a factory reset and carefully repeated all the set up steps I'd previously done - including the Google services permissions. For me; turns out the culprit was the Night Light setting - when it's set to 'Turns on from sunset to sunrise' it prevents the R5 from going to sleep (power button flashes blue) and drains the battery. I've set it to a custom time, the device now sleeps correctly and the battery drain has gone.
Hope this might help.