Seized Brake Caliper Question

Good morning, I have a 2002 NB2 that I installed non sport size brake pads and rotors into the rear. I found this out when getting an alignment. About a week later, I’m driving casually and I start to hear a terrible scraping sound. I take the car home and take off the old rear rotors and pads. The rotors look fine, however the pads on the back left are COMPLETELY worn out, and then pads on the right are only slightly worn. I try to compress my calipers, and the left one won’t compress at all, however the right caliper compresses just fine. I’m assuming I have a seized caliper. Is there anything else I should check before I order replacement calipers, pads and rotors? Thank you