LCD causing overheat?

[AC Question]

So we bought a galaxy s6 active under a year ago and it began to overheat to the point you could not even touch it and would not charge, it took about 7 hours to fully charge. We tried dafe mode and it did not help at all and also tried to factory reset it. Since it was still in warranty we sent it into samsung and they fixed the LCD screen. Could the LCD screen cause those problems or does the problems with the LCD screen come from the overheating?