I disagree completely on who’s responsible, not that it should matter because it’s not our job to diagnose and fix the problem.
If these fancy high-capacity lithium systems were the same as a flooded- or AGM-based motorhome, it wouldn’t have taken years to get to where we are today with the technology, or a couple of years for Thor to try to catch up with Volta and Xantrex systems, or Roadtrek’s EcoTrek before that. The average “technician” may not have a clue what he’s dealing with. And all of these previous systems had plenty of early design and quality issues of their own.
In my opinion the thing that’s getting out of control is the sentiment that RV owners are somehow responsible to fix problems themselves, or worse yet that they should understand what’s causing the problem in the first place. That may work for a few hands-on owners, but will never be the norm. Not in today’s world.
If an air conditioner doesn’t cool enough, should a home or RV owner know why it’s not cooling more? It may help but that knowledge shouldn’t be necessary to own an air conditioner. You call a qualified A/C contractor or repair person and let them figure out what’s wrong. That may not be ideal from a cost standpoint, but it’s reality for most people today.
The one thing most of us expect is that the A/C “expert” can figure out what’s wrong on his own.
In this case I feel for the OP. If the problem was that simple to fix, or was operator error, why didn’t first tech find it and fix it? And if it’s more complicated than “very simple to fix”, why should the owner be expected to diagnose it himself?