I want to reset my iMac (late 2014, 1 TB Fusion Drive) to factory settings. As I want to set it back to Yosemite, I am using Internet Recovery (Command-Option-R) as I have installed El Capitan in the meantime.
I was able to erase the HDD just fine in Recovery Mode Disk Utility, but now I am stuck.
First Aid Verify Disk doesn't show any anomalies either from what I can tell ("The volume ... appears to be OK"). First Aid Repair went through without issues, but that didn't change anything. Tried rebooting several times but that didn't help either. I also tried El Capitan Recovery mode (just holding Command-R without Option), it looks a bit different, but the overall result is the same.