Bu40n 1.00 Firmware -

LG BU40N 1.00 is regarded as the premier "DE" firmware for enabling full UHD 4K ripping capability on slim LG drives, offering superior compatibility with MakeMKV over newer versions

Open MakeMKV. Look at the "Drive Information" panel. Note the "Firmware version." If it is 1.00, you are done. If it is higher (e.g., 1.03 or 1.14), proceed. bu40n 1.00 firmware

offers the best software compatibility across various ripping and playback tools, not just MakeMKV. Reliable Read Speeds LG BU40N 1

Because most BU40N drives now ship with versions 1.01 to 1.05, users typically have to "downgrade" or "cross-flash" their hardware using community tools. 1. The Necessary Tools 1.03 or 1.14)

Note: You will find it on LG’s official support site – they only host newer versions.