Welcome to Vodafone Community
Having done a software update not so long ago my galaxy note 4 has become very unresponsive and turns itself off. Sometimes when it's on I get a blank screen and have to take the battery out and put it back in to get it going. Sometimes I get the message pictured and I don't know what to do when it appears i have done a factory reset
Please let the phone index for a few days ie Settle down from the Software Update and factory reset.
Another option is to put the phone in Safe Mode which disables all your downloaded apps and leaves the stock apps alone which can help to highlight if its a rogue app. Then deleting each one in turn should help to highlight the possible culprit.
Also some apps maybe just catching up with the new update and looking to see if any updates for your apps might help.