2014 iMac 27" 5k no hard drive found?

Right after the last Apple event I ordered a new Mac Studio to replace my 2014 iMac. In the meantime my iMac had a kernel panic and when I rebooted it there was the prohibit sign and wouldn't boot. I booted into Recovery and Disk Utility didn't see my internal drive, it only saw the Fusion drive. I figured the hard drive probably gave out since it's 8 years old. However I ran Hardware Diagnostics and it did show anything.

I was planning on selling the iMac once the Studio came in. Now I have a dead iMac with a drive that has everything still on it. Even though the test didn't show any hardware problems I figured I could put another drive in and at the very least get the old drive out. So I ordered the exact model of Seagate 1TB drive that was in there. Installed the drive and put everything back together, booted into Recovery and again it doesn't show up. I can't format it because it's not there. I did all this with the screen still loose so I unplugged the drive and plugged it back again thinking that maybe it wasn't seated correctly. Still no-go. Ended up just sealing the screen.

I'm here to see if there was/is anything I could do? I would assume if there was a controller or something out the hardware test would've showed that? I guess the old thing got jealous of the new Mac Studio coming and just gave up! I don't want to get into spending a bunch getting it to do something but I'm open to any suggestions.

Thanks