prisi Well, I had (and always have) the same concern about bricking my phone.
But the guy who made the video says it's almost impossible to mess up if you follow his instructions. I will say that, from my experience installing Graphene twice on my phone, in my opinion, the most critical factor is to NOT interrupt the install; at each step, be sure to let that step complete.
In the video I suggested, you'll see him doing the install on his phone. When the screen on your phone shows the messages he points out at each step, you'll know that the step in question has completed.
One other thing is that you need a good cable. Some cables are power only cables, not data transfer cables. Be sure you have a good data cable (that of course also supports charging). The video discusses this of course.
I'm sure others have had equally positive experiences doing it another way. This just worked well for me.