I bought the S5 Sat and through out the day and the next day i was receiving the same message, even when i was using the phone, i took the battery cover off and put it back on correctly at least 50 times. I took it back to the store the next day to have it looked at. The owner took the back off and put it back on several more times. He called Samsung to see what they said and the customer support person stated they have not received any calls about this before and did not know what to do, they said they would look in to it and call him back in 24 hours.
The store owner got another back cover from a new phone and told me if it continued to bring it back and he would swap it out with a different S5. And if Samsung had any help on this matter he would let me know. I had to return to the store the next day because I had the same results. He had not received a call back from Samsung yet but went ahead & pulled another S5 and gave me that one. With this new phone i do still get the message when i re-boot as is normal, but every time i wake the phone i get the message too, at least this one does not show the message when i am using it like the last one. I went to the store on Wed to let the owner know this for future reference and to see if he received a call back from Samsung, but as of yet he still has not received a call back from Samsung. He did tell me that his brother has the same phone and the message comes up when he turns the phone off and re-boots, and the only other time he gets the message is if he takes off the cover. He does not get the message when he wakes the phone like i do unless the cover is messed with, so it seems to be a problem or irritation on random phones, and it does appear to have a sensor for the cover because it knows the cover has been taken off on others phones because that is the only time they get this message.
I would love to know how to get this fixed or get the message disabled. I get this message now at least 15-20 times a day with out re-booting, just waking it up to use it and the message shows up.