Today we don't have just one story about a Samsung Galaxy S4 bursting into flames... we have two! First, a 13-year old girl fell asleep with her Samsung Galaxy S4 under her pillow. At some point in the night it caught fire and began burning through her pillow and sheets. Luckily, she awoke from the smell of something burning before it harmed her in any way.
While there are obviously valid points to make regarding the unwise decision to sleep on your smartphone, it turns out this wasn't just her fault, furthermore, it wasn't Samsung's fault either. The father of the device later admitted to replacing the battery with a third party battery which was not on Samsung's approved parts list. It seems that neither person in this family made the smartest choices which lead to this event. Above is a Dallas, TX local news affiliate report on video of the story.
Source: BGR

The second event we have to report has a happy ending too, and makes HTC look good. A Reddit user named TweektheGeek posted on Reddit that his Samsung Galaxy S4 overheated and partially melted one night. (His SGS4 was not under his pillow and did not have a third party battery.)
He went through the usual procedure of contacting Samsung for a replacement, and sent it back. Samsung assured him that they would replace his device, but he never received it. An HTC product manager named Leigh Momii caught his story on Reddit and decided to seize the moment as a marketing opportunity. She sent him a brand new HTC One M8 as a replacement for his burned up Galaxy S4. The only condition that she stipulated was that if Samsung ever sent him a replacement, he would need to give it to charity.
Although this was an obvious PR stunt, we can't help but applaud the savvy way she took advantage of the opportunity.
Source: AndroidAuthority