Actually, it is very expensive to open an IP67 protected smartphone against water and dust. The iPhone 8 Plus does this under certain circumstances but apparently alone: Two users reported that the device has burst. Apple is already investigating cases. However, there is no reason to fear that a similar debacle will take place at Galaxy Note 7 in 2016.
With one of the users, the iPhone 8 Plus has ruptured as Apple's, when it's just charged - well with the original accessories. The second owner should have already received the device in this state. According to the pictures, the front of the smartphone has detached itself from the housing, due to a swollen battery.