Anything that saves me $800+ and doesn't require an unnecessary (and ill-advised repair) makes me verrrryyyy happy!!!
I am going to talk to the shop tomorrow. Before I tell them what I found, I am going to ask if they still feel the cluster replacement is the way go to. And whether they want to do any further troubleshooting first.
If they say yes to the repair and no on the troubleshooting, I am going to tell them what I found. And that I am going to be looking for a new repair shop. I won't have any confidence in them next time something comes up.