Samsung's Galaxy Note 7 was one of the most infamous smartphones in history, and not for a good reason. The Galaxy Note 7 was announced in August 2016. It went on sale later that month for a couple of weeks then it was recalled because the devices were exploding or catching on fire. In September, Samsung started selling the device once again, as it thought it had figured out the issue and fixed it. Instead, the issue still persisted and Samsung was forced to do an unprecedented second recall on the Galaxy Note 7. But there are still some out there with the Galaxy Note 7 in their hands. Which means they are likely pretty stubborn. Since Samsung has pushed out software updates that effectively made the device useless.
Now, there are a few users posting in the Galaxy Note 7 subreddit claiming that the battery is beginning to swell, and might explode soon. Which is mostly like what's going to happen, as that's just physics. When a battery begins to swell, it's going to explode sooner or later. There are a few other users also noting that their device is beginning to do the same thing. If you do still have the Galaxy Note 7 in your possession, please return it to Samsung. It is a fire hazard, and no one should have one in their possession. As it could lead to some serious damage to you or your property.
Those that do still own a Galaxy Note 7 should be upgrading to the Galaxy Note 8 or even the Galaxy S9 Plus. It's a device that Samsung would like for everyone to forget about, even though it does talk about it at every smartphone launch. And Samsung also talks about how its testing its smartphones before it sells them, now, to reassure everyone that these smartphones are indeed safe.