It's one thing to fix things for yourself, and a whole other kind of thing to hold yourself out to the public as an expert in something. Kind of like how you can defend yourself in court but not someone else unless you are a lawyer. Though I would be surprised if the law were written such that you couldn't repair someone else's device, so long as you did not receive compensation for it.
The problem is that it sounds like the device manufacturer gets to decide what certifications are sufficient. Presumably they could decide that no certifications are sufficient, and thus no one can run a certified repair shop.
Or they could offer their own certification, but make attaining it prohibitively expensive or difficult.
So as a non-certified repairer, you have to offer a city tour around the block, at a ridiculously high price, and then repair the device at no additional cost. All a matter of perspective.
