About six months after moving into my house I was fed up with the janky garage door opener that came with it so I went to Home Depot and bought a new one. I managed to assemble the new one myself with only a few hiccups. It then came time to remove the old garage door opener. I first took down the actual motor unit that was attached to the ceiling and got it set on the ground with the rail still attached. The end of the rail was attached to a metal bracket that formed a right angle with lots of holes for bolts to go through[0] which was then attached to the drywall above the garage door. I got up on a ladder and set to removing the bolts. The last bolt, unbeknownst to me, was attached to a piece of metal through which the garage door spring went [1].
What happened next all tool place within maybe 1/4 a second. As soon as I turned the socket wrench enough to loosen the bolt I heard a loud pop and felt something hit my hand. HARD. I looked down at my hand and saw blood. "No big deal, I cut myself on things all the time. We've got lots of bandages." Then I noticed the subcutaneous tissue (your hand doesn't have much, but there's still enough that deep cuts look different). "Okay this is gonna need stitches, I better get down and take care of this." And then I saw the bone. "ohfuckohfuckohfuck."
I hopped down off the ladder and ran inside and started screaming "CALL 911!!!" to my girlfriend who was upstairs. I made it to the kitchen where I got a dish towel, put my hand on the counter, and clamped down as hard as I could. The paramedics arrived about 5 minutes later (we live very close to a fire station). By then I'd calmed down but was so full of adrenaline I could barely hear or see anything. At one point I blanked out for maybe 30 seconds? I'm not entirely sure. The EMT said it was an adrenaline dump and that it was fairly normal. Of course when I got to the ER every single nurse who heard the story said I was lucky to be alive. If it had hit my head it would have caved in my skull (and I was on a ladder...). Apparently that happens more than you'd think.
They eventually hooked me up with a drip of hydromorphone. "This is the good stuff." one nurse said. Bullshit. I was in so much pain it barely did anything. It brought it from 10/10 to 9.5/10. That's using my new 10 point scale. I thought I'd experienced a 10 before when one time my dentist started drilling before the lidocaine had fully kicked in. I'd put that at about a 6 now. I really cannot describe in words how bad the pain that night and the following months was.
My hand is a lot better now though. The third surgery gave me back my mobility and the physical therapy got me back up to about 60% of the strength I had before. I'll never be able to point straight with my right index finger, but I can make a fist and type. As a programmer both are very important.
[0]: Exactly like this https://mobileimages.lowes.com/product/converted/040395/0403...
[1]: Basically this, except mine is shaped slightly different http://www.truetex.com/gar913.jpg