"After assembling my QMX+, applying power, and pressing the encoder switch, I saw 170 mA current draw but no LCD backlight and no USB port recognition."
This is normal. You then need to load the firmware operating system from your computer. After loading, it should automatically boot with the model selection screen and the backlight on.?
What's not normal is not seeing the QMX show up on your computer. Try a different cable or a different computer.?
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73, Dan? NM3A