Yes this totally fixed it, thank you so much.

I just finished setting everything up, but when I tested it in the AOI setup, I still got the blank white screen.

I have burnt an image of retro pi to an SD card before with a pi zero. I followed the steps laid out by this video https://www.youtube.com/watch?v=xvYX_7iRRI0. I downloaded retro pi 2/3 using the link https://retropie.org.uk/download/, extracted the file, formatted the SD card, and wrote the program...

I hope this helps

I have formatted the card with SDformatter and I used win32disk imager to write the retro pi 3 program to the card

I have plugged in everything in order to perform a test start up before I put the case together. But the screen only shows 'BC1' when the power is turned on. What did I do wrong and how can I fix this?

Solution: Use the pre-made image from the Circuit-Sword GitHub page