To cut a long story short, I have an Acer Swift 3, purchased in May 2020, then replaced anew in October 2020 after the original was written off by the insurance company (don't ask).
It has now developed a persistent fault, which I'm done with trying to fix. Basically, all CPUs are stuck at 0.4 GHz after 20 seconds, Windows or Linux, nothing changed software-wise, can't control fans since proprietary controller, basically it's going to have to be repaired by Acer. I've even pushed cool air through it externally to check it wasn't thermally throttling.
What I'm not sure about is whether the original warranty is void (since the replacement came from a different retailer), and whether it restarted with the replacement model (exact same model). Do I go back to the retailer that supplied the replacement, or to the original company (who don't even know it was replaced by the insurance company), or go to Acer NZ direct?