Wanted to have my Mac Mini boot from an SSD rather than the stock 5400 HDD.
I installed the new drive as per the guide. The only issue was that the SSD was not recognized in the slot that the guide instructed me to put it in. I then flipped the locations of the SSD and HDD and everything else worked as planned
I did some digging on the internet and some models don't allow an SSD to go where an optical device is expected. So once I flipped the locations of the drives everything worked fine.