MacBook Air and new SSD

a friend had her 2013 MBA SSD replaced by a larger SSD from OWC. This happened just last week. The work was done by a Mac specialist. It worked ok for a week, then suddenly it would not open up. The OS progress bar got so far,then it shut down the MBA. So I opened it in restore mode, checked the SSD for repair and it returned a huge number of directory errors. It will not repair and instructs me to erase, replace OS.
Unfortunately the MBA is in France and the Mac specialist is in the UK.
So...

MacBook Air and new SSD