Try adjusting the display contrast. The display contrast is a parameter that can only be accessed from the Theremini’s Advanced Menu. To get to the advanced menu, start on the Theremini’s main screen (the screen with the tuner). Press SETUP and SCALE at the same time. While holding down SETUP and SCALE, turn the PRESET encoder one click to the right. You are now in the Advanced Menu. Press SETUP until the display reads “Contrast…..xx”. Now, turn the PRESET encoder to get the desired LCD contrast. Once you have the desired contrast, press SETUP to return to the main screen.