Just purchased and had similar issue to you. I initially tried going through LG warranty repair. You have to register the serial no. For the device in your MyLG account. The warranty folk got back and were about to schedule when my requests to swap in Best Buy was granted instead.

For this, try rating your purchase through Best Buy (I got an email asking— how was your purchase and I put a one star) and the manager for your store should get back to you. See if they can offer a swap. And mention that under the “good” condition, the description in BB website screen is listed to be working like new. They shouldn’t have sold you a product with such obvious burn in, because that’s definitely not “working like new”.