FaceTime HD Camera (Built-in) detected on USB hub, but no picture? `sudo Killall VDCAssistant`, restarting, etc does nothing
You most likely have a hardware failure of the Facetime camera.

It doesn't have to show up in AHT for there to be a problem.  Like any test, AHT isn't immune to false positives/negatives.  

To truly verify if it's your hardware or software, install a generic USB camera (FaceTime camera is technically a USB camera) which uses the same underlying software as the FaceTime cam.  If it works, it's a hardware issue.

Regarding your AHT error code indicating a bad drive; just because it uses the code "HDD" doesn't mean it's not applicable to SSDs.  An SSD or HDD uses the exact same ATA command set to interface with so if you are getting an error code it is valid and applicable.

Again, AHT is not the definitive answer, but a tool to help you diagnose problems.  If it's giving you an error code, it's something you should start looking into.