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.