It's been months since the Samsung Galaxy Note 7 was discontinued in the market. There were been a number of unofficial reports of why it was happened on the Note 7 and earlier, the officials from Samsung Mobile finally revealed the true findings.
In a post from their Samsung Newsroom site, they had over numerous devices were brought from their elaborate tests which they found two issues. The first batch of batteries was affected by a design flaw in the upper corner
In a normal state, negative and positive electrodes were apart from a protective layer. If the damage will hit on the protective layer which brought some incidents of exploding Note 7 units,
You can check the more complex details from their link here