I know this is an old post but it's still a problem. For some reason, (I have a Nokia 7.1) and about 2/3 weeks ago, bluetooth started turning it's-self on. I'm not going to say 'Automatically' becasue there were no devices in range and the phone had no reason to switch bt on. I scoured the internet, found several 'solutions' including turning off bluetooth scanning, followed all the instructions and thought I'd cured it, but alas it was only temporary. I got in touch with Nokia and after several e-mails and attempts at sorting it, I was advised to restart the phone in 'safe' mode. That way, only the pre-installed apps would work and all the 3rd party apps would be disabled. I did what I was advised and hey presto, the problem went away. This proved that it was a 3rd party app which was causing the problem. Unfortunately, I have about 40 apps installed and it would have been a major pain in the arse to disable each one in turn in order to identify the guilty app. I didn't want to do it but my only option was to carry out a full factory reset. I backed up my data to Google, then reset the phone. If you follow this proceedure, be careful not to allow the phone to 'copy' your backed up data back to the phone as this will restore the problem. When you sign into the clean phone with your Google account, stop ALL attempts by Google to copy your backed up data back to the phone. The very first thing you must do is open the Google Play Store App and stop apps from updating automatically. I resisted the temptation to start downloading any apps or carry out any updates and the phone behaved normally for 24 hours. After that time I began to re-install just a few important apps, 'weather', 'whatsapp', etc 5/6 at a time, then let them do their thing for about 12 hours before downloading any more. I've now gone for 24 hours with no problems. I decided during this operation that I wasn't going to clutter up the phone with apps that I only use a couple of times and would stick to the bare essentials. I now have only about 10 3rd party apps on my phone instead of the original 40 odd, I have a phone that runs smoothly, quickly and doesn't make me feel like throwing it through the window 10 times a day.