Is the problem in the code or in the OLED screen?

I see what you mean now about the 37th element. That actually exists, although you won't find it in the array but in this if statement

  if ((digitalRead(Key) == 1) && (fadeValue2 != 36))

It serves the purpose of telling the code to start calculating the password.

And thank you very much for the advice, I wonder if by fixing the inputArray boundaries by terminating it and by changing the value of the digits 0-9 will finally allow the code to run. Will definitely fix those two things and report back!