Return it for a refund. I have confirmed the player is registered as a device in my Amazon Prime account and it still won't stream Amazon Prime or Netflix videos.
I have three LG smart TVs and have been perfectly happy with them but the BP350 is the WORST LG product I have encountered. It flat refuses to play ANY Prime Videos and half of the Netflix content I tried wouldn't play. Additionally, the Blu-ray capabilities are mediocre at best. I have full 1080p HD cables, have done all the software updates, turned-down the streaming quality (something I SHOULDN'T have to do) and it just doesn't do anything well but play DVDs as well as a $30 ONN, Walmart's invented brand, at three times the price of an ONN brand! Simply stated, this product does NOT do what it is advertised to do.