phandad

In 2019 I purchased the "main board" (EBT64292506) for my not quite 3 year old OLED55B6P-U TV from Encompass Parts. (The "main board" has the HDMI ports). https://encompass.com/item/11061882/LG/EBT64292506/ You should be able to find the part number somewhere on your old board. After installing the board, the new board the TV powered up with the "Factory Mode Floating Box". See this post for my solution: https://www.lgwebos.com/topic/2591-factory-mode-floating-text-box/

See this post: https://www.lgwebos.com/topic/2591-factory-mode-floating-text-box/#comment-14233

I'm definitely not an expert, but in today's world, your download speed is slow. I believe the bigger the screen size and more resolution a device has, more info has to be downloaded for a given image - a phone screen doesn't need much, but a 86", probably 4K or better TV, needs a lot more. I'd love to have someone with more knowledge than I confirm my thoughts.

I had this same "Factory Mode" problem when replacing the main board (EBT64292506) on my not quite 3 year old OLED55B6P-U TV. Did some web searching and found an LG "Factory SVC Remocon" MKJ39170828 - it has the "In Stop" button. Purchased it for less than $10. One push of the button and my TV was back to user mode ready for initial setup.