I guess I should chime in on this thread since I was the seller.
First off congratulations on getting this pin so far along in such a short period of time. I am glad it found a good home.
I know I sent the pin to you with the plugs unlabeled, I hope that is not what is causing you the trouble. When I got the pin it was in pieces and I never attempted to get it running so I did not want to label anything if I was not 100% sure it was correct.
If you are getting so many weird switch issue I would make very sure you have the plugs into the right spots. It seems like you either have them mixed up or perhaps one is inserted one pin off, i.e. the plug is shifted with one pin outside of the connector.
I would look at the wiring diagram and just trace out one wire fully from a switch to the plug to verify that you have the right plug in the right spot.
Sound issue:
I don't see the two wire connector that runs to the speaker plugged into the sound board. Take a look for that two pin plug and get it plugged into the sound board. I think the two wire plug that goes to the speaker goes onto the #1 & 2 pin of the J2 connector on the sound board. Two plugs go onto the J2 connector on the sound board the two wire and I think a four wire connector. Sometimes there in one big plug, sometimes there are two, like with your pin. At least that is my memory with most of the squawk and talk boards. I am hoping someone can chime in with what goes where on them. Overall the sounds boards have never given me any trouble over the years, so I don't have a real clear memory of what goes where on them.
That bent up mess of pins in the double row on the sound board is not used, don't worry about it. I would just make sure none of the pins are bent so much that they are touching each other.
Overall, I would just say check and make sure all of the plugs are where they are supposed to be. You only need to verify one wire per plug(I work on the assumption that the wires were not all mixed up on the plug(s)). Look at the wiring diagram and find the easiest thing to get access to that goes to that plug and use your ohm meter to verify that it is that wire. You can also look at the wire color code also, but I have sometimes had weird issues with the color changing when it goes through various wire harness inline plugs. The ohm meter continuity test is the for sure way to know what is going where.