Mirror lies now in the holder, scratches are easily seen. And there are lot of those... Remove mirror from the holder. Put it on soft cloth or a piece of lens paper (to avoid any other damage).
On backside of faulty mirror there is a "signature". This most propably refers to quality checking. Either the person performing quality control, did not actually check the mirror, or scratches have been made in the mirror installation phase. TV quality control -> alert, alert...
Based on "signatures", replacement mirror has been checked by two persons...
Mirror holder has two thin strips of soft foam inside, to press the mirror against diagonal body. I am bit worried about this material. How does it work after long time, ten years or more ? Is it still flexible enough to support the mirror ?