Question: High Sierra upgrade failure on 27" iMac
A few days ago I tried to upgrade to the latest High Sierra OS on my mid-2009 (I think) 27" iMac and it has failed - somewhat spectacularly I think. I could use some help. The machine ran perfectly fine before the upgrade attempt.
Initially, the same oft-reported hang-up at the "Calculating installation time" prompt was occurring and the installation would crash. This occurred several times (5+) before I decided to try booting in recovery mode. In recovery mode I have run Disk Utility/First Aid on the internal SanDisk Ultra II SSD I installed several years ago and I keep getting an "Operation failed" message. Specifically, the message states, "First Aid process has failed. If possible back up the data on this volume. Click Done to continue." There are a number of "Invalid extent entry," "Incorrect size for file," "Overlapped extend allocation," and other messages in the Details log with the final two being; "An internal error has occurred" and "Operation failed."
I briefly looked into Reinstall macOS in Recovery Mode to simply load a new copy of Sierra on the hard drive, but the SSD drive did not appear on the list of available drives - only my backup drive with my Time Machine backups appeared.
It would seem as though the upgrade attempt has bricked my hard drive. What should I do next?!
iMac, Mac OS X (10.7.2)