The letter doesn't seem to be saying the tests don't work, or that they're vaporware. It is only finding "noncompliance". Looking at the first item, "Hematology" (https://www.law.cornell.edu/cfr/text/42/493.1215), it could just be that one of the conditions here (https://www.law.cornell.edu/cfr/text/42/493.1269) wasn't met. Those look pretty easy to fix!

Of course, yes, there could also be all sorts of crazy sketchy voodoo. Ya never know.