I had this same problem on an ipad air. after i replaced the screen it became possessed, like someone was typing and opening programs. it worked perfectly with the screen laid in place but but when i installed it i put small cracks in the flex cables by not inserting them down in the case side and they got pinched between the screen and case . so once cracked they can’t be repaired. So i got a new screen but this time i kept the screen up on its edge so as not to stretch the cable . then when you start to lay the screen on the ipad the cable tucks into the case space better. same also when installing the display keep the display supported on its edge on you may crack the cables . So that’s the fix for the possessed ipad don’t stretch or crease the cables
No its not damaged. i had the same problem /message .open up the phone and pull the sim card ,sd card and remove the mid frame. Just above the usb charge connector you will see two small gold contacts that touch what i believe is the temp sensor which is located in the mid frame assembly.Clean the two contacts on that sensor with a q tip dampened with rubbing alcohol.You may also have to be careful and slightly bend upward those two springy contacts that touch the temp sensor. Hope this works for you it fixed my S4.