Black screen of death

Hello. I am new to this forum, and new to Android smartwatches. I am experienced in Android in general. I do not have a watch yet, but I am planning on soon buying the Zeblaze Thor. I was originally going to buy the Fossil Q Marshall, but I thought it might be more fun to have a watch that runs 5.1 Lollypop, rather than one that runs Android Wear. I am very glad that there is a forum like this, and that there are developers for the watches.

I have a question: I have heard of the possibility of bricking your watch by having a black screen that gets stuck on the screen. How is this caused, and how to avoid it?