zevia posted link to new 1655 firmware a few hours ago.
I flashed 1655’s BCDB firmware on my 1640 using BQFlasher. BQFlasher flashed drive without errors, but after flash drive stopped to respond.
Restarted and tried The Dangerous Brothers DOS flasher (BENQCVT) but the drive is not seen in dos or windoze anymore.
My advice; don’t even try to flash your 1640 with 1655’s BCDB.exe firmware!
Also posted a warning in above linked thread.