This sent me on an Internet dive.
The injury happened on a kickoff return. Reports said that Burnett collided head to head with a blocker. I was able to find a video (not surprisingly, most outlets have taken it down), but it’s unclear what happened — it’s a gang tackle, several players go to the ground, and apparently everyone but Burnett got up. Burnett was on the field for several minutes, and players were gathered in prayer, but he gave a “thumbs up” sign from the backboard as he was wheeled off the field and the game went on. One report I saw from immediately after the game mentioned the injury in passing; other reports didn’t mention it at all. It sounds like Burnett’s condition took a turn for the worse a day or two after the injury; by Thursday (five days after the game), it was clear that his condition was grave.
It’s tempting to say that this is another data point in favor of abolishing the kickoff, but from the footage I saw it appears that the injury could’ve happened on any short-yardage play — it was a gang tackle, and Burnett was one of the tacklers.
