2010 Mac Mini SSD will not boot up
My Mac Mini 2010 had a new 250 ssd hard drive fitted 4 years ago, today it will not boot up. When starting up using Command-R the disk utility says that the Mac HD is not mounted, taking it to an iCare center only got the response it is vintage and no parts available, not interested in repairing, so how do you remount it, any suggestions please, thank you.
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Mac mini, macOS 10.13