It was a bit of a problem trying to follow your assembly and disassembly. Sounds like you tried to remove one too many pins or the wrong pins. You only need to push out two pins, in order to drop the trigger group/housing, out. These two pins will practically fall out. There is a bolt stop and it's the furthest pin on the back side of the reciever. That one can be hard to remove and sounds like you mistakenly removed this one and your bolt was allowed to drop down on top of the trigger housing. .....
You really don't have to send it in, just go to u-tube and your will find a ton of videos on this process. I routinely take these apart, even down to removing the safety. when i started doing trigger work on these, the first videos I looked at, were in U-Tube !! ..
Good luck and;
Be Safe !!!