HL-DT-ST DVDRAM GHB0N help needed

I have an Hitachi HL-DT-ST DVDRAM GHB0N which, I understand from A.I.D is actually an Hitachi-LG, that comes with revision 1 firmware, manufacture date is 2014 Serial Number KBOE6RG1331. Having spent hours looking for rpc1 firmware, or even just newer firmware, I have encountered nothing except dead links.
I understand from this link LG GHB0N Drive Identification and Crossflash that the drive is probably crossflashable but all links in thread are dead
Can anyone kindly help me to update the firmware in the drive please?
Any help greatly appreciated.