Sorry! I was reading "ROM" as in a read only memory
. Like you had two nexuses and one was newer and had a different/newer eeprom or something (indicating a fixed firmware for the video -> screen) or something.
So this ROM just makes it easier to boost brightness/constrast like you can do with screen adjuster? I don't think that's a full fix then...just fixes some cases of the black levels and not the color banding.