On the Subject of Negativity

It’s called “Negativity” but not “Positivity”? I demand opposition equality!

• The module consists of a touchable screen, an input display, a Submit button, and a Clear button.
• The screen cycles 10 different three digit numbers, some with a minus sign, and either with a white background or a black background.
• For all the numbers shown:
  • If the background colour is white, then use the number as is.
  • If the background colour is black, then negate the number.
• Add all the numbers up.
• After you get your answer, press the Submit button. This will stop the cycling of the numbers, and the screen will flash between white and black moderately.
• Convert the answer gathered into balanced ternary. Then remove all zeros in the result.
• Input the resulting ternary from most significant digit to least significant digit.
• Press the screen when it is white to input a plus, and when it is black to input a minus.
• If you are satisfied, press the Submit button to submit the input.
• A strike will be given for inputting the wrong answer, and it will cause the module to reset.
• You may hit the Clear button to clear your input.
• You may also hit the Clear button when the input display is empty to resume the cycling of the numbers.