re:
I'm experiencing similar issues with my Note 8. Phone gets extremely hot and this is after my local Samsung Service Centre has replaced motherboard and battery. Right now, with the phone basically sitting idle, temperature is 39.8 centigrade which is well above the 27 degrees mentioned by BADhominid. When actually in use, the phone gets noticeably hotter. I only just installed the Ampere app so I will post an update once I have a better picture of the temperature.