I just want to share an incident that higlights the consequence of not understanding the basics of belaying and the belay device. I was not in the gym when the accident happened, but I will try my best to describe the accident.
On July 28, two of my friends were climbing at Hoosier Heights gym in Bloomington, IN. The ropes in the gym have a permanent grigri attached to them. The belayer was in the gym for the second time and had gone through the belay lessons. After a couple of routes, as the belayer was lowering the climber, she got her brake (right) hand pinched between the grigri and the rope. She panicked, let the rope go off her brake hand and for some reason also opened the lever with her left hand. The climber fell around 10-15 feet on the gym's padded floor.
The X-ray and CT Scan revealed that he has a fracture and there is an 80% damage to the spinal canal. Usually this means paralysis, but fortunately that was not the case with my friend and he was still able to move his hands and feet. Last week, a spinal fusion surgery was done to fix his back and he is recovering in the hospital now.