I have just finished assembling the 737 MCP. Before starting programming I did a test connecting the Arduino boards via USB. This brought power to the boards and therefore I thought that all the 8 digits displays should light up. 4 out of 5 displays did, but the fifth did not.
My question is: Is it right of me to assume that these displays should light up when I connected the USB, or will this display light up when I start programming the boards?