Dometic 2-Way fridge repair issues

Hey everyone, I've got a 1995 Salem Travel trailer with a Dometic 2-Way fridge. Fridge wasn't working when purchased (no power in the upper controls), but after looking into it I thought I could fix the problem.

So as it stands right now I don't have the gas function operating (battery won't hold its charge) but I am plugged into shore power. 

I've opened up the access panel at the back of the fridge to the control board and started doing some poking around. I grabbed a multimeter and started checking my connections. I was getting 120v at the plug (that the fridge is plugged into), 120v going into the board from the plug, and 120v at my fuse on the control board. Although I went and tested the connection between the main control board and the upper control board (the two buttons at the top of the fridge) and I wasn't getting any read on power going to the upper control board. 

This made me believe that my main control board had gone faulty seeing as I was getting power to it and through it, but not out of it. I then purchased a replacement board from amazon that matched my product number of the old board (2932177.01) and installed it, triple checking that my connections were in the right spot. 

Once everything was plugged in I went to check to see lights on the upper control board and still nothing. Went back to the main board with my multimeter and still wasn't getting power going to my upper control board connection, even on a brand new board.

I'm honestly lost as to what it could be. The only thing I can think of is if the board needs both systems operational to allow use (120v and 12v both working). Or maybe I'm crazy in thinking that. In my mind it should work without needing the 12v from the battery, then again could be completely wrong. 

I would appreciate any suggestions, thanks.