It was behind the head unit. After removing the head unit, I realized that I didn’t have to go to all that trouble. It was easiest to reach up behind the unit from the passenger floor well. It was easier to see when I removed the head unit. However, after I had it fixed and knew where everything was, I realized that I could have reached everything without removing all of those interior pieces. If I remember correctly, the amp is held in place by 4 bolts, and then all the wiring is long enough to reach the passenger side floor (or almost long enough) and it’s easier to work with there.
Good luck!