Wow, but not surprising at all. I'm sorry you are experiencing such difficulty.
This ordeal simply exemplifies my grievance's with the overuse of technology in the everyday automobile. One can hardly hold any 'mechanic' at fault for such problems. Certainly not a dealer that, through no fault of their own, was essentially nearly put out of business because the manufacturer pulled out. Those guys are certainly not computer geniuses', electronics experts or IT pros as most are not. It appears due to the low volume of cars experiencing even fewer problems requiring a direct link to Japan, they haven't had to get practiced at this 'connecting' business. Skills, or anything else, not used are generally lost. I had mentioned that their factory trained guys are long gone as a warning. This episode is remarkably similar to what we experience in the automation world constantly. Far too many things changing randomly, with out any direct knowledge, results in 'things' ceasing to function or operating predictably, including the 'tools' required to connect to, program, diagnose or query the tech. Everything needs and internet connection to somewhere anymore to gain permission, the token, to allow one to simply to observe what's going on inside just about anything. They may have simply taken a windows update, with or without their knowledge or understanding or awareness that something so innocuous could cause a problem with something the rarely, if ever, use. Believe me, that's all it would take to cause their failure to connect or a host of other issues with this entire process.
I wish you all the luck and hope that they can straighten out your car w/o breaking the bank. And please keep us up to date. Thanks.
2010 Kizashi GTS, CVT, iAWD (3/10 build date)
2011 SX4 Premium Hatch, CVT, iAWD (12/10 build date)
2018 Mazda CX-5 iAWD Touring
2014 Wrangler JKUW (GONE, traded
1991 Samurai, 5-Speed, EFI, Soft-Top (