This Grandstand Firefox F7 was badly corroded to the logic board. I have extensively cleaned it and reflown every solder joint. Alas, the two columns right of the centre one do not display properly. They are very faint and as can be seen, some detail is missing. Is this a CHIP issue? Is it repairable or is it finished? I know that you can pass extensive current but I'm not sure this is a phosphor issue? Any advice before I scrap it would be hugely appreciated. Many thanks in advance