You need to go to test mode and calibrate the vol L and R inputs. You can also edit /contents/prop/ea3-config.xml to change language to English:
<soft>
<model __type="str">KFC</model>
<dest __type="str">A</dest> <-- set this line to A for English, J for Japanese -->
<spec __type="str">F</spec>
<rev __type="str">A</rev>
<ext __type="str">2021060802</ext>
</soft>