Galaxy J7 back button and recent apps buttons not working

[zalong50]

My galaxy j7's back button and recent app button isn't working and I already tried restarting my phone and using safe mode but their still not working. I noticed this problem when I was trying to take a picture, I pressed the power button and on the lock screen it says to swipe the screen, then it would take you to where you draw the pattern but it kept going back to where it says to swipe the screen. That is when I restarted my phone and discovered the problem with the buttons.

UPDATE: The recent app button on my phone was working for about an hour and now its stopped again.

 

[Ralston18]

Two thoughts to offer:

Hopefully a buggy update - something fixable via a rollback or patch.

Or, something physically broken.

Any warranty?