@Pat Hey there. I don’t work for Lockitron, but I’ve been around these forums for a while. I just took the back off my Bolt to investigate. There’s a teardown somewhere online, but I don’t believe it showed this part in detail.
The positive terminal is the first one on the left, on the bottom, and the negative terminal is the last one on the right, on the bottom. Those are the ones that need power.
Now, I had a quick look at what your adapter looks like, and as long as those dummy batteries continue the circuit (like a jumper wire) from one terminal to the other, then it works. If those dummy batteries don’t let power through, then it doesn’t work.
Since your power battery is in just one terminal, it won’t power it on it’s own unless something connects the negative spring from the top to the main one on the bottom left.
That being said, there may be something on the Lockitron bed regulating this - I think we’d need @Cameron to follow up.