Can anyone tell me what I did?

[SaxonPig]

Trying to install new spring and buffer in a Marlin Model 9. Could not get the pin back in the front of the receiver. Jiggled it for an hour with no success. Could not make all those holes line up.

Then I discovered I had a bigger problem. The trigger and hammer are frozen. It looks to me like the hammer is at half-cock (see photo) and it's stuck (well, I can push it back and forth a bit but that's it). The trigger is also immobile.

How did I do this? Can I undo it?

 

[Riss]

Looks like you might have a part in backwards or a part overriding another where it should not be. Be PATIENT so as to not bend anything or gouge out the holes. Try taking all the pins back out to loosen things back up and try again. Sometimes there is a specific order and sometimes parts look like they will go in both ways but only go in one way.