On previous Galaxy Note smartphones, it was either impossible to insert the wrong way or required substantial force so you'd immediately realize you were doing something wrong, but with the new Galaxy Note 5's S Pen this is not the case. The pen slides in with exactly as much resistance as inserting it the right way and will get stuck. If you try to remove it with force, chances are you'll break the device's pen detection sensor:
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.Samsung was reportedly aware of the issue when it shipped the Note 5, the Note 5 manual even contains a specific warning message that inserting the pen the wrong way can damage the pen and your phone.