At that point, other GM dealers refused to look at it without taking a large up-front deposit.
Corporate didn’t actually use the words “pound sand”. It would have saved me time if they had.
Eventually, I took it to a Chevy dealer, and they upgraded the radio firmware. The electical problems were caused by a CAM protocol bug that prevented the ABS from powering off sometimes.
This was all in the first 1000 miles.
It had unrelated issues due to the fake parts, but the dealer “honored” the warranty by switching them out for a different brand.