An individual purchased an Deye inverter. Possibly from someone selling within or into the US, possibly bought it themselves overseas and carried or had it sent here.
Is that (all of the above possible cases) illegal?
If the individual did not enter into a contract saying they would not operate it in the US, I think they could operate it here. Especially if they were the importer.
If manufacturer Deye bricked it, they can take up a dispute with Deye.
But if US based SolArk pressured Deye to brick it, perhaps SolArk is financially responsible for the damage caused.
You aren't allowed to bring a trademark violating "Disney" object into the US.
You are allowed to bring a knock-off fake Rolex.