I am running Big Sur. My PC died but all working again. Now, due to new AIO CPU cooler, I upgraded from 11.6.4 to 11.6.8. All ok. But, when I try to update to Monterey, it fails and just restarts Big Sur. I have tried updating SYMBIOS from iMac 18,1 to iMac19,1. Is it possible to go to Monterey?