"What to do when you screw up 2,000 orders"
https://www.sparkfun.com/news/1575Ouch..
Let me just say that when you actually manufacturer a product, one of the worst feelings ever is when you start getting customers calling saying their thing isn't working right and you realize you screwed something up. That feeling of relief you get when you finally ship some stuff under the gun is very very quickly replaced by wanting to crawl in a hole and die. Oh the joys of engineering manufacturing.
Good thing I've never made a $50,000+ USD mistake.... I'd still be crying..