Sounds like a good one and hearing they tried to help is often good to hear!
But then I also find trying to help is as much a PR act as it is not truly real people who know what is needed. Maybe sales folks as much or more than repair folks?
So I fall back to DIY on a number of things!
Looks like you have the good info to ID a manual when you find the correct one! Good start!
I found this sheet of various frig manuals and went to troubleshooting 2018 to current. Thinking you frig might fit that age group?
That section has this chart to first test the DC operation than AC.
https://static1.squarespace.com/stat...gGuide2018.pdf
Does this fit anything the builder had you try and in an organized way?
This might be the best way I would see for a DIY test to check what I might find.
As a small side point that I have found in my work? Things can get corroded or a bit loose where we don't expect them. When checking things like fuses of breakers, wires, etc. give them a bit of close look and maybe wiggles them a bit.
You could have just enough corrosion at some point or maybe just a wire that is still almost broken but sometimes good, sometimes bad?
Hit and miss stuff is the worst but you may get lucky enough to avoid the trauma of replacing the frig and that is worth a lot for poking around at things.
This is a group that always likes to know how it goes, so please do tell us some good stories if they come around??