Always shut down your device using the shut down menu.
Frozen android TV box, bricked android TV box, android TV box freeze, android TV box stuck in standby in most cases starts because some genius told you "Just take the power lead out".
Think about it, if you bought a mobile phone and downloaded an app that required you to remove the battery every time it needed to run something what would you think of this app? AVOID!
You find these ill informed geniuses when you try and install Kodi community builds or when some wannabe android TV box seller copies someone else's work changes a few file locations and says "Run my amazing wizard to get my amazing build". Just don't. These people may know a small amount of copy and paste in Kodi language but when it comes to Android they know very little or nothing at all. There is a shut down menu for a reason, use it or if you want a nice collection of paper weights keep doing it.
Below is how you should close a frozen app properly and how to shut down correctly. There are rare occasions when you must remove the power to breakout of app freeze but if you avoid the community builds and the copy and paste programmers you will ensure your android TV box runs well for years.
On your android TV box press the home
button then select..
Setting > More settings > Apps > Kodi > Force close