Re: Note 4 Update
If the update is running and something happens around 25%, it should give you a "failed" notice - that's around the point at which it checks whether the phone's ever been rooted and, if it has, stops the update process. (Updating a phone that has been rooted can brick it, even after you unroot it.) It sounds as if the update code got a but corrupted, failed at the root check (even if the phone's never been rooted), then "went walkabout" - just wandered off like a 99 year old with severe Alzheimer's. (Software can do that - it;s why software is tested before it's released.)
Papa, if it's still stuck, make sure it's fully charged, then bring it into a Sprint store and ask them to help you. (Turning the phone off at this point may just leave you with a not-updated phone that's working perfectly or it may brick the phone. Let them be responsible if they brick it.)
Or, if you prefer, bring it into a Best Buy, go to the cellphone area and look for the Samsung rep. (He or she will be wearing a light blue polo shirt with a Samsung logo.) Same thing - if someone is going to brick the phone, let it be someone other than you. (Samsung, if they brick the phone, can flash the ROM to it - you'll lose your data, which you should always have backed up anyway, but you'll have a working phone.)