I don't watch any wrestling, and I'm not very familiar with this man's career, but a couple things I noticed lead me to believe this may be fabricated as part of a staged stunt.
I was a firefighter for 4 years and if he truly was unconscious while being strapped to the backboard his hands would not be locked like they are on his chest. Limp unconscious bodies are more fluid and for the most part spider straps need to be used to secure the person to the backboard. Notice how his arms straight and his hands are on his chest/abdomen. He then appears to regain consciousness and reach into his pocket (it appears...)
That said, it doesn't necessarily mean that this is fake, but the way that first thing falls on the stage accompanied by explosions and flashes, and then how the sign falls on the stage giving him a 'protected' space to duck into seems to indicate this was meant to be stunt.
That does not mean that the stunt went well and he didn't get hurt in the process, but from my seeing this for the first time on this video it would appear to be iffy.
Itay.