[eric12341]

Try hard resetting it . U can also remove the advanced configuration app as it has known to cause problems related but not exactly similar to the one u described . Another thing u can do is try a different rom I personally recommend vins latest neodium rom without CHT. if u don't want to or know how to flash a custom rom then I recommend u download and flash the stock 6.1 rom as that is faster and more stable than the stock 6.5 rom
. If none of these solve ur problem then u may need to get another replacement.