Just wanted to say thanks for this comprehensive guide. I did have some issues using rootmytv - my LG firmware has patched that so it didn't work so I had to downgrade it. That was a bit of a faff but dropping back to firmware version 05.30.10 allowed me to complete the process.
Firmware can be obtained here for my TV.
https://web.archive.org/web/20210416163649/https://www.lg.com/uk/support/product/lg-49UK6300PLB.AEK