If possible, flash in windows safe mode in the future.
However, due to a failed flash, you need to recover the drive from the damage.
Recovery is done by forcing any compatible firmware onto the drive using a DOS startup floppy disc and a DOS-based flasher. Create a startup disc, download DOS flasher software plus a compatible firmware and put these onto the startup disc. Download directions for the operation of the DOS based flasher software. Power off the computer and then start it up using the startup disc. If necessary, configure the motherboards bios to allow starting up with a floppy disc. Force factory standard firmware onto the optical drive.
Whoah! Stop. I wrote this in the wrong order. First, diagnose basic connectivity issues:
Is the drive master of the secondary IDE channel alone on a good quality IDE cable?
Is the motherboard set to auto detect with auto type the master of secondary IDE so that it will load full support?
If there was previously a different optical drive installed as master of secondary IDE, you may need to reset the motherboard's CMOS so that it will recognize correct parameters of the BenQ drive.
Rarely, with an older motherboard, you will have to force UDMA=OFF using bios settings or by setting master of secondary IDE=none (this is a rare need and certainly not the first thing to try).
With connectivity issues out of the way and factory standard firmware forced onto the drive, it is now in an "known good" condition and ready to retry the upgrade. Furiously tap the F8 key during computer startup and direct it into "Safe Mode" before using the windows based upgrade flasher.
If you're lucky, firmware B3JCY will be available to flash onto the drive in DOS mode and you can skip a few steps. However, this will cause permanent damage (drive=trash) if DOS mode flashing is done while connectivity issues are present.
Best of luck!