Samsung Galaxy Note5 has earned some extra popularity these days, not due to it being a successor in the highly successful Note series of phablets, but for carrying a major flaw. We had already reported that inserting the S Pen in the wrong way can damage your Note5.
 samsung galaxy note5, note5 stylus
However, now we know the real reason behind this. Now we know how the mechanism, which houses the S Pen in place, works. A teardown of the Samsung Galaxy Note5 was carried out by 9to5Google for finding out the hidden details under the body of the phablet. A lever was discovered after the teardown and is responsible for locking the S Pen in place when it is inserted the wrong way in.
samsung galaxy note5, note5 inside
Secondary Lever (Circled), Can Disable the Auto-Detection Feature If Damaged

It is not an easy task to remove the stylus after it has locked inside in the wrong position. You may try to wiggle the S Pen to remove it, but there is actually another lever which stands in place. This additional lever touches the stylus slightly and can break easily. Repairing this secondary lever isn’t an easy task either. In case you break the smaller lever, the auto-detection functionality of the S Pen will be lost, resulting in you not being able to use some features such as the lock screen memo advertised by Samsung.

So you know now that inserting the S Pen of the Note5 in the wrong way can cause a great damage. Even Samsung provides this warning somewhere inside the user manual. So be careful when using the S Pen and do not be tempted to insert it wrongly.