The GBC-H20N is just an unnecessarily crippled GGC-H20N. It can be flashed back to a standard GGC-H20N easily;
- Go to device manager, locate the BD-Rom drive, right click it and uninstall
- Press and keep holding the eject button on your GBC-H20N and restart your computer, keep holding eject till your back on the desktop
- Let go of eject
- Go back to device manager and scan for new hardware, your computer should find your BDRom drive and identify it as a GGC-H20N.
- Download the latest firmware here
- Install the new firmware
I can confirm this works and adds support for HD-DVD. I’ve tried and tested this method today! HD-DVDs read fine :).
BTW: I take no responsibility if you damage your drive.