Version 1.00 is a "UHD-friendly" firmware that allows software like MakeMKV to bypass AACS 2.0/2.1 protection on 4K Blu-rays.
Do NOT use the stock LG 1.03. You need the "MK" (MakeMKV patched) version. Search for the (available on the MakeMKV forums). Inside the tool, you will find a pack of firmware files. Look for: bu40n 100 firmware hot
If you are looking to "hot-flash" or downgrade your drive to version 1.00: BU40N firmware question - www.makemkv.com Version 1