Yep, serial cable required for issuing commands at the shell prompt.

And, something that's becoming a rarity these days, an actual honest-to-God serial port on your PC for flashing new firmware or disk builder images onto the player. The USB-to-serial dongles that are available for laptops these days are iffy and might not work for that task.

Make sure to go through that whole list, don't just check for a loose IDE cable. There's a lot of items on that list besides a loose IDE cable.