Presumably "no faults with the charging system" simply means that the units went again through some standard factory tests, and passed. In fact these standard tests probably (hopefully) evolved a bit, it would actually be interesting to read more details about that.
And I am not sure how one can "rule out overcharging" at this stage ... does it simply mean that some thresholds were not (never?) exceeded for some measured physical values (which ones?) and if so, the statement is rather weak.