I just posting my a update I found recently for the firmware on the DH-20A4H liteon drive firmware. Seems like both the Global and US firmware look like they match. But here are both links. I downloaded the Global and updated my firmware for my drive.
Global
http://www.liteonit.com/global/index.php?option=com_wrapper&Itemid=154
http://www.liteonit.com/DOWNLOADS/ODD/DH-20A4H/firmware/QP5B.rar
US
http://us.liteonit.com/us/index.php?option=com_wrapper&Itemid=153
http://www.liteonit.com/DOWNLOADS/ODD/DH-20A4H/firmware/QP5B.rar