We try not be hyperbolic here at Android Police, so allow me a moment to explain our title here, and why we think it is justified.
It is extremely rare that a modern, expensive electronic device ships with an easy-to-encounter design flaw that can result in apparently permanent, or at least not easily corrected, damage to the device. At this point, we feel strongly that the S Pen in the Galaxy Note 5 does suffer from a design flaw that will be encountered by some end users of the device, a flaw which could permanently break a feature of the phone.
The flaw stems from Samsung's new S Pen slot design on the Note 5, and you may have read about this already elsewhere, but here's our take on it. Basically, on previous Galaxy Note smartphones, attempting to inset the S Pen in the device in the wrong direction resulted in obvious futility - they won't fit, or if they do, they require substantial force to get into the S Pen slot the wrong way, enough that you'd immediately realize you were doing something wrong.
On the Note 5, inserting the S Pen the wrong way provides exactly as much resistance as inserting it the right way. Which is to say: basically none at all. Once you insert the pen far enough in the wrong direction (again, which causes no strange resistance or feel than putting it in the right way), it will get stuck. It doesn't even have to "click" in. At this point, of course, you will panic. And you will try to get it out - and most likely, you'll succeed. The problem is that if you do succeed, there's a very real possibility you'll break whatever mechanism the device uses to detect whether the pen is attached or detached from the phone. Which is exactly what happened to our review unit.
Yes, seriously. Watch the video.
We're really not sure how this made it past testing at Samsung - it seems like such an obvious thing to design into the S Pen slot, especially when Samsung has full reason to know that inserting the pen the wrong way can damage the direction-sensitive detection mechanism in the slot.
Pen detection on our review unit is completely broken, and during the making of this video in an attempt to show how easy it is to insert the stylus the wrong way, the S Pen became hopelessly jammed in the slot, and I am now totally unable to remove it without the assistance of tools I'd rather not try, in the interest of avoiding further damage to the device. The reason we did this was simple: to see if the defect, which we'd read about elsewhere, was real. It seems very real to us.
We will be reaching out to Samsung for a statement on this, and in the meantime, advise everyone with a Note 5 to be exceptionally careful to make sure you don't insert the pen in the device in the wrong direction (and by relation, maybe don't let your kids play with the stylus, because yeah). We can only speculate what action Samsung may take, but I would have to think either a new S Pen stylus design must be implemented that cannot cause this problem (and pens can be provided free of charge to owners), or the devices themselves should probably be recalled.
This is highly unusual, and not the kind of engineering we expect from a company of Samsung's caliber.