Define scratches. Use enough water and paper towel to clean the whole glass surface. It is better to mark the scratches down.
Before Repair
Keep Spray water during the repair to cool the glass
Tear down the backing plaxtic of the diamond lapping fikm down
Judge the depth of scratches. Use the green diamond lapping film for deep scratches. Keep the bottom tray clean and dry. Tear down the backing plastic of - the diamond lapping film down and stick the diamond lapping film to the bottom tray. Spray water on the glass surface. Hold the grinder tight. Make the strength, even and let it operates just against the glass surface. The following grinding should covers 1/2 to 2/3 of the former grinding. Spray water consistently and avoid irregular grinding. When green diamond lapping film is finished grinding. Move the grinder away. And the scratches are already removed.