this issue could be caused by a fault in the board if your phone gets very hot on the back and shows a red light and if and when it dose boot it should refuse to charge that is if its cable is plugged in and also if the light remains a solid red that little led indicates something is wrong maybe faulty obviously that's a good guess considering that light is also just responding for charge power input this I know but what I'm saying is if your screen wasn't black before you may want to unplug the screen connector cable but before you do anything pop up the flex cable for the battery otherwise you may accidentally get an electric shock that is not good so unplug the battery remove the Philips screws only top and mid section row if you want to fully inspect your board but don't forget to take out the cameras and sim before fully removing the motherboard if that still doesn't work id buy a new phone cause the s8 active screens are stupidly expensive paying a premium of about 100 dollars eBay or ifixit just for...