Hello fellow community members, I need your help to resolve my issue. I have been searching for the past few days frantically and still not able to solve my issue. I sincerely hope that someone here can help me find a solution. I have a 2010 Imac 27 in with a built-in HD (1-TB). I had added an internal SSD (240GB) a few years back and kept the original HD as well. The computer has been running fine. I have been using my SSD as my primary boot drive and the HD still had the old OS software on it. Two days ago, I decided to upgrade the SSD software to macOS High Sierra. The installation took a very long time and I was able to get to the initial login screen and while I was trying to add my Apple ID the computer got stuck and I had to hard reset using the power button. The iMac only rebooted to the old software on HD and would not boot to SSD anymore. I have been reading that this may be due to SSD issue not being compatible with HS upgrade (APFS) volume but I am not 100% sure. Here is what I have done so far. I have an external Hard drive (4TB) that I created few partitions and on one of the partitions I installed a fresh copy of macOS HS (thinking that it will be APFS volume which would help me read my now APFS converted SSD but I still cannot read the data off of my SSD. when I boot to my fresh copy of SSD, and using the disk utility, I can see the iMac SSD-240 (disk2s1) however, it is greyed out and I cannot mount it. I clicked "Mount" many times but nothing happens. This is the SSD which is internal to the computer and have all my data that I need to access. [Unfortunately I have never created a time machine back up of my SSD] Not sure what else can I post here, but my ultimate goal is to get the data from the SSD (APFS) before I can format it and do a fresh install. If there is a way to fix the SSD to make it bootable again, I would love to try that. Please let me know if there is any other information I can provide to explain my issue. I am in dire need of the help and looking forward to the help from community on my issue. I have installed the macOS HS on the partition named "OS-HS" on my external USB hard drive iMac SSD-240 is the SSD that is internal and have the data to be recovered from. more information on the SSD. I have also tried the following command using terminal: Type This Into Terminal: diskutil list | grep --regexp=.*disk2.* This is what the commands returns. Still not seeing this in my finder's tab. This is what Disk utility shows after running the command. SSD still remains unmounted. clicking the "mount" does not do anything.