Hello - I just ran into a similar issue with a bricked BU40N after trying to flash it with the LG 1.05 firmware updater. Neither SDFtool nor the ASUS flashers worked, however I found this one from Dell: https://www.dell.com/support/home/pl-pl ... erid=hn7y6
To my surprise, this one worked to unbrick it, although it's back to 1.03 firmware.
Give it a try and see if it unbricks your drive. It can't hurt at this point.