And this is why I hate all the newer cars (actually, within the past 15 years at least). It's all the crazy computer issues that spring up. As just one example only, hubs uses his code reader to identify the problem going on behind (whatever warning light comes on the dashboard). What happens, is that it's rarely ever just ONE issue -- it could be a number of different codes that appear, of "possible" issues.
So what the dealers and private repair guys do, is start with the most common issues, and work their way down the list to "fix" the problem. (Some rather unscrupulous repair people will cherry pick the more expensive ones first, and work down the list that way.
) Really lucky that hubs knows a lot about cars and used to (years ago) be a licensed mechanic. So he's done various repairs himself on our car, but certainly not everything (as he doesn't have all the necessary tools that the repair shops have). The good thing is that he knows how to talk to mechanics. (I wouldn't have a clue what to say, and am sure I'd be way overcharged.)
Anyway, determining which repair code problem is creating the actual issue, can sometimes be trial and error (even for top mechanics) -- similar to your software "upgrade". Perhaps something didn't quite "take" in the upgrade and it needs to be done again, or, it may not be that at all. Hoping all they need to do, is just redo the upgrade only.
I'm certainly no car mechanic; but I do know from various guys I've known down through the years, that prior to so much computerizing cars, the car problems were a lot clearer, as well as the repairs that followed.